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<!-- DFIN ActiveDisclosure(SM) XBRL Linkbase Document - http://www.dfinsolutions.com/ -->
<!-- Creation Date      : 2022-02-25T20:16:15.3647647+00:00 -->
<!-- Version            : 5.0.1.728 -->
<!-- Package ID         : 68048d2a21e84ec998859347dc959714 -->
<!-- Copyright (c) 2022 Donnelley Financial Solutions, Inc. All Rights Reserved. -->
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    <link:loc xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_EntityFilerCategory" xlink:type="locator" xlink:label="dei_EntityFilerCategory" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityFilerCategory_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Filer Category</link:label>
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    <link:label xml:lang="en-US" xlink:label="dei_EntityFilerCategory_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Entity Filer Category</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_EntityShellCompany" xlink:type="locator" xlink:label="dei_EntityShellCompany" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityShellCompany_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Shell Company</link:label>
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    <link:loc xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_EntitySmallBusiness" xlink:type="locator" xlink:label="dei_EntitySmallBusiness" />
    <link:label xml:lang="en-US" xlink:label="dei_EntitySmallBusiness_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Small Business</link:label>
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    <link:label xml:lang="en-US" xlink:label="dei_EntitySmallBusiness_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Entity Small Business</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_EntityCommonStockSharesOutstanding" xlink:type="locator" xlink:label="dei_EntityCommonStockSharesOutstanding" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityCommonStockSharesOutstanding_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Common Stock, Shares Outstanding</link:label>
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    <link:label xml:lang="en-US" xlink:label="dei_EntityCommonStockSharesOutstanding_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Entity Common Stock Shares Outstanding</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_EntityPublicFloat" xlink:type="locator" xlink:label="dei_EntityPublicFloat" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityPublicFloat_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Public Float</link:label>
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    <link:label xml:lang="en-US" xlink:label="dei_EntityPublicFloat_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Entity Public Float</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_EntityFileNumber" xlink:type="locator" xlink:label="dei_EntityFileNumber" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityFileNumber_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity File Number</link:label>
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    <link:label xml:lang="en-US" xlink:label="dei_EntityFileNumber_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Entity File Number</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_EntityTaxIdentificationNumber" xlink:type="locator" xlink:label="dei_EntityTaxIdentificationNumber" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityTaxIdentificationNumber_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Tax Identification Number</link:label>
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    <link:label xml:lang="en-US" xlink:label="dei_EntityTaxIdentificationNumber_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Entity Tax Identification Number</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_EntityAddressAddressLine1" xlink:type="locator" xlink:label="dei_EntityAddressAddressLine1" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityAddressAddressLine1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Address, Address Line One</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_EntityAddressAddressLine1" xlink:to="dei_EntityAddressAddressLine1_lbl" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityAddressAddressLine1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Entity Address Address Line1</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_EntityAddressCityOrTown" xlink:type="locator" xlink:label="dei_EntityAddressCityOrTown" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityAddressCityOrTown_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Address, City or Town</link:label>
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    <link:label xml:lang="en-US" xlink:label="dei_EntityAddressCityOrTown_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Entity Address City Or Town</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_EntityAddressStateOrProvince" xlink:type="locator" xlink:label="dei_EntityAddressStateOrProvince" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityAddressStateOrProvince_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Address, State or Province</link:label>
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    <link:label xml:lang="en-US" xlink:label="dei_EntityAddressStateOrProvince_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Entity Address State Or Province</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_EntityAddressPostalZipCode" xlink:type="locator" xlink:label="dei_EntityAddressPostalZipCode" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityAddressPostalZipCode_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Address, Postal Zip Code</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_EntityAddressPostalZipCode" xlink:to="dei_EntityAddressPostalZipCode_lbl" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityAddressPostalZipCode_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Entity Address Postal Zip Code</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_EntityIncorporationStateCountryCode" xlink:type="locator" xlink:label="dei_EntityIncorporationStateCountryCode" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityIncorporationStateCountryCode_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Incorporation, State or Country Code</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_EntityIncorporationStateCountryCode" xlink:to="dei_EntityIncorporationStateCountryCode_lbl" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityIncorporationStateCountryCode_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Entity Incorporation State Country Code</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_CityAreaCode" xlink:type="locator" xlink:label="dei_CityAreaCode" />
    <link:label xml:lang="en-US" xlink:label="dei_CityAreaCode_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">City Area Code</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_CityAreaCode" xlink:to="dei_CityAreaCode_lbl" />
    <link:label xml:lang="en-US" xlink:label="dei_CityAreaCode_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">City Area Code</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_LocalPhoneNumber" xlink:type="locator" xlink:label="dei_LocalPhoneNumber" />
    <link:label xml:lang="en-US" xlink:label="dei_LocalPhoneNumber_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Local Phone Number</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_LocalPhoneNumber" xlink:to="dei_LocalPhoneNumber_lbl" />
    <link:label xml:lang="en-US" xlink:label="dei_LocalPhoneNumber_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Local Phone Number</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_SecurityExchangeName" xlink:type="locator" xlink:label="dei_SecurityExchangeName" />
    <link:label xml:lang="en-US" xlink:label="dei_SecurityExchangeName_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Security Exchange Name</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_SecurityExchangeName" xlink:to="dei_SecurityExchangeName_lbl" />
    <link:label xml:lang="en-US" xlink:label="dei_SecurityExchangeName_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Security Exchange Name</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_Security12bTitle" xlink:type="locator" xlink:label="dei_Security12bTitle" />
    <link:label xml:lang="en-US" xlink:label="dei_Security12bTitle_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Title of 12(b) Security</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_Security12bTitle" xlink:to="dei_Security12bTitle_lbl" />
    <link:label xml:lang="en-US" xlink:label="dei_Security12bTitle_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Security12b Title</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_IcfrAuditorAttestationFlag" xlink:type="locator" xlink:label="dei_IcfrAuditorAttestationFlag" />
    <link:label xml:lang="en-US" xlink:label="dei_IcfrAuditorAttestationFlag_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">ICFR Auditor Attestation Flag</link:label>
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    <link:label xml:lang="en-US" xlink:label="dei_IcfrAuditorAttestationFlag_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Icfr Auditor Attestation Flag</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_AuditorFirmId" xlink:type="locator" xlink:label="dei_AuditorFirmId" />
    <link:label xml:lang="en-US" xlink:label="dei_AuditorFirmId_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Auditor Firm ID</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_AuditorFirmId" xlink:to="dei_AuditorFirmId_lbl" />
    <link:label xml:lang="en-US" xlink:label="dei_AuditorFirmId_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Auditor Firm Id</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_AuditorName" xlink:type="locator" xlink:label="dei_AuditorName" />
    <link:label xml:lang="en-US" xlink:label="dei_AuditorName_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Auditor Name</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_AuditorName" xlink:to="dei_AuditorName_lbl" />
    <link:label xml:lang="en-US" xlink:label="dei_AuditorName_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Auditor Name</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_AuditorLocation" xlink:type="locator" xlink:label="dei_AuditorLocation" />
    <link:label xml:lang="en-US" xlink:label="dei_AuditorLocation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Auditor Location</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_AuditorLocation" xlink:to="dei_AuditorLocation_lbl" />
    <link:label xml:lang="en-US" xlink:label="dei_AuditorLocation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Auditor Location</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementOfFinancialPositionAbstract" xlink:type="locator" xlink:label="us-gaap_StatementOfFinancialPositionAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StatementOfFinancialPositionAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Statement Of Financial Position [Abstract]</link:label>
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    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AssetsAbstract" xlink:type="locator" xlink:label="us-gaap_AssetsAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AssetsAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">ASSETS</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_AssetsAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Assets [Abstract]</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_AssetsCurrentAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Current assets:</link:label>
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    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xlink:type="locator" xlink:label="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Cash and cash equivalents</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_ShortTermInvestments_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Short-term investments</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_ShortTermInvestments_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Short Term Investments</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_AccountsReceivableNetCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Trade accounts receivable, net of allowance for doubtful accounts of $3.6 and $2.0 at December 31, 2021 and 2020, respectively</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_AccountsReceivableNetCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Accounts Receivable Net Current</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_InventoryNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Inventories</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InventoryNet" xlink:to="us-gaap_InventoryNet_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_InventoryNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Inventory Net</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherAssetsCurrent" xlink:type="locator" xlink:label="us-gaap_OtherAssetsCurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OtherAssetsCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other current assets</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherAssetsCurrent" xlink:to="us-gaap_OtherAssetsCurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OtherAssetsCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Other Assets Current</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AssetsCurrent" xlink:type="locator" xlink:label="us-gaap_AssetsCurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AssetsCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total current assets</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AssetsCurrent" xlink:to="us-gaap_AssetsCurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AssetsCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Assets Current</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentNet" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PropertyPlantAndEquipmentNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Property, plant and equipment, net</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PropertyPlantAndEquipmentNet" xlink:to="us-gaap_PropertyPlantAndEquipmentNet_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PropertyPlantAndEquipmentNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Property Plant And Equipment Net</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeaseRightOfUseAsset" xlink:type="locator" xlink:label="us-gaap_OperatingLeaseRightOfUseAsset" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseRightOfUseAsset_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Right-of-use assets</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingLeaseRightOfUseAsset" xlink:to="us-gaap_OperatingLeaseRightOfUseAsset_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseRightOfUseAsset_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease Right Of Use Asset</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_Goodwill" xlink:type="locator" xlink:label="us-gaap_Goodwill" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_Goodwill_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Goodwill</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_Goodwill" xlink:to="us-gaap_Goodwill_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_Goodwill_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Goodwill</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsNet" xlink:type="locator" xlink:label="us-gaap_FiniteLivedIntangibleAssetsNet" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Intangible assets, net</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsNet" xlink:to="us-gaap_FiniteLivedIntangibleAssetsNet_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finite Lived Intangible Assets Net</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongTermInvestments" xlink:type="locator" xlink:label="us-gaap_LongTermInvestments" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LongTermInvestments_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Long-term investments</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LongTermInvestments" xlink:to="us-gaap_LongTermInvestments_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LongTermInvestments_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Long Term Investments</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherAssetsNoncurrent" xlink:type="locator" xlink:label="us-gaap_OtherAssetsNoncurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OtherAssetsNoncurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other assets</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherAssetsNoncurrent" xlink:to="us-gaap_OtherAssetsNoncurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OtherAssetsNoncurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Other Assets Noncurrent</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_Assets" xlink:type="locator" xlink:label="us-gaap_Assets" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_Assets_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total assets</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_Assets" xlink:to="us-gaap_Assets_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_Assets_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Assets</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:type="locator" xlink:label="us-gaap_LiabilitiesAndStockholdersEquityAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LiabilitiesAndStockholdersEquityAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">LIABILITIES AND STOCKHOLDERS&#8217; EQUITY</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:to="us-gaap_LiabilitiesAndStockholdersEquityAbstract_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LiabilitiesAndStockholdersEquityAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Liabilities And Stockholders Equity [Abstract]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LiabilitiesCurrentAbstract" xlink:type="locator" xlink:label="us-gaap_LiabilitiesCurrentAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LiabilitiesCurrentAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Current liabilities:</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LiabilitiesCurrentAbstract" xlink:to="us-gaap_LiabilitiesCurrentAbstract_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LiabilitiesCurrentAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Liabilities Current [Abstract]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShortTermBorrowings" xlink:type="locator" xlink:label="us-gaap_ShortTermBorrowings" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShortTermBorrowings_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Short-term debt</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShortTermBorrowings" xlink:to="us-gaap_ShortTermBorrowings_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShortTermBorrowings_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Short Term Borrowings</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccountsPayableCurrent" xlink:type="locator" xlink:label="us-gaap_AccountsPayableCurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AccountsPayableCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accounts payable</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccountsPayableCurrent" xlink:to="us-gaap_AccountsPayableCurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AccountsPayableCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Accounts Payable Current</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EmployeeRelatedLiabilitiesCurrent" xlink:type="locator" xlink:label="us-gaap_EmployeeRelatedLiabilitiesCurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EmployeeRelatedLiabilitiesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accrued compensation</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EmployeeRelatedLiabilitiesCurrent" xlink:to="us-gaap_EmployeeRelatedLiabilitiesCurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EmployeeRelatedLiabilitiesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Employee Related Liabilities Current</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccruedIncomeTaxesCurrent" xlink:type="locator" xlink:label="us-gaap_AccruedIncomeTaxesCurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AccruedIncomeTaxesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Income taxes payable</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccruedIncomeTaxesCurrent" xlink:to="us-gaap_AccruedIncomeTaxesCurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AccruedIncomeTaxesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Accrued Income Taxes Current</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeaseLiabilityCurrent" xlink:type="locator" xlink:label="us-gaap_OperatingLeaseLiabilityCurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseLiabilityCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Lease liabilities</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingLeaseLiabilityCurrent" xlink:to="us-gaap_OperatingLeaseLiabilityCurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseLiabilityCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease Liability Current</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ContractWithCustomerLiabilityCurrent" xlink:type="locator" xlink:label="us-gaap_ContractWithCustomerLiabilityCurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ContractWithCustomerLiabilityCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Deferred revenue and customer advances</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ContractWithCustomerLiabilityCurrent" xlink:to="us-gaap_ContractWithCustomerLiabilityCurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ContractWithCustomerLiabilityCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Contract With Customer Liability Current</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherLiabilitiesCurrent" xlink:type="locator" xlink:label="us-gaap_OtherLiabilitiesCurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OtherLiabilitiesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other current liabilities</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherLiabilitiesCurrent" xlink:to="us-gaap_OtherLiabilitiesCurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OtherLiabilitiesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Other Liabilities Current</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LiabilitiesCurrent" xlink:type="locator" xlink:label="us-gaap_LiabilitiesCurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LiabilitiesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total current liabilities</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LiabilitiesCurrent" xlink:to="us-gaap_LiabilitiesCurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LiabilitiesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Liabilities Current</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongTermDebt" xlink:type="locator" xlink:label="us-gaap_LongTermDebt" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LongTermDebt_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Long-term debt, net</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LongTermDebt" xlink:to="us-gaap_LongTermDebt_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LongTermDebt_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Long Term Debt</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredIncomeTaxLiabilitiesNet" xlink:type="locator" xlink:label="us-gaap_DeferredIncomeTaxLiabilitiesNet" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredIncomeTaxLiabilitiesNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Non-current deferred taxes</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredIncomeTaxLiabilitiesNet" xlink:to="us-gaap_DeferredIncomeTaxLiabilitiesNet_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredIncomeTaxLiabilitiesNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Income Tax Liabilities Net</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EmployeeRelatedLiabilitiesCurrentAndNoncurrent" xlink:type="locator" xlink:label="us-gaap_EmployeeRelatedLiabilitiesCurrentAndNoncurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EmployeeRelatedLiabilitiesCurrentAndNoncurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Non-current accrued compensation</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EmployeeRelatedLiabilitiesCurrentAndNoncurrent" xlink:to="us-gaap_EmployeeRelatedLiabilitiesCurrentAndNoncurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EmployeeRelatedLiabilitiesCurrentAndNoncurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Employee Related Liabilities Current And Noncurrent</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeaseLiabilityNoncurrent" xlink:type="locator" xlink:label="us-gaap_OperatingLeaseLiabilityNoncurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseLiabilityNoncurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Non-current lease liability</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingLeaseLiabilityNoncurrent" xlink:to="us-gaap_OperatingLeaseLiabilityNoncurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseLiabilityNoncurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease Liability Noncurrent</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherLiabilitiesNoncurrent" xlink:type="locator" xlink:label="us-gaap_OtherLiabilitiesNoncurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OtherLiabilitiesNoncurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other non-current liabilities</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherLiabilitiesNoncurrent" xlink:to="us-gaap_OtherLiabilitiesNoncurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OtherLiabilitiesNoncurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Other Liabilities Noncurrent</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_Liabilities" xlink:type="locator" xlink:label="us-gaap_Liabilities" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_Liabilities_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total liabilities</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_Liabilities" xlink:to="us-gaap_Liabilities_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_Liabilities_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Liabilities</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommitmentsAndContingencies" xlink:type="locator" xlink:label="us-gaap_CommitmentsAndContingencies" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CommitmentsAndContingencies_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Commitments and contingencies (Note 23)</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommitmentsAndContingencies" xlink:to="us-gaap_CommitmentsAndContingencies_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CommitmentsAndContingencies_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Commitments And Contingencies</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockholdersEquityAbstract" xlink:type="locator" xlink:label="us-gaap_StockholdersEquityAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockholdersEquityAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Stockholders&#8217; equity:</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockholdersEquityAbstract" xlink:to="us-gaap_StockholdersEquityAbstract_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockholdersEquityAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stockholders Equity [Abstract]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PreferredStockValue" xlink:type="locator" xlink:label="us-gaap_PreferredStockValue" />
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    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PreferredStockValue" xlink:to="us-gaap_PreferredStockValue_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PreferredStockValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Preferred Stock Value</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockValue" xlink:type="locator" xlink:label="us-gaap_CommonStockValue" />
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    <link:label xml:lang="en-US" xlink:label="us-gaap_CommonStockValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock Value</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AdditionalPaidInCapitalCommonStock" xlink:type="locator" xlink:label="us-gaap_AdditionalPaidInCapitalCommonStock" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AdditionalPaidInCapitalCommonStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Additional paid-in capital</link:label>
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    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RetainedEarningsAccumulatedDeficit" xlink:type="locator" xlink:label="us-gaap_RetainedEarningsAccumulatedDeficit" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RetainedEarningsAccumulatedDeficit_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Retained earnings</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_RetainedEarningsAccumulatedDeficit_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Retained Earnings Accumulated Deficit</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:type="locator" xlink:label="us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accumulated other comprehensive (loss) income</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Accumulated Other Comprehensive Income Loss Net Of Tax</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockholdersEquity" xlink:type="locator" xlink:label="us-gaap_StockholdersEquity" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockholdersEquity_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total stockholders&#8217; equity</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockholdersEquity" xlink:to="us-gaap_StockholdersEquity_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockholdersEquity_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stockholders Equity</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquity" xlink:type="locator" xlink:label="us-gaap_LiabilitiesAndStockholdersEquity" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LiabilitiesAndStockholdersEquity_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total liabilities and stockholders&apos; equity</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LiabilitiesAndStockholdersEquity" xlink:to="us-gaap_LiabilitiesAndStockholdersEquity_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LiabilitiesAndStockholdersEquity_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Liabilities And Stockholders Equity</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent" xlink:type="locator" xlink:label="us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Allowance for doubtful accounts</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent" xlink:to="us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Allowance For Doubtful Accounts Receivable Current</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PreferredStockParOrStatedValuePerShare" xlink:type="locator" xlink:label="us-gaap_PreferredStockParOrStatedValuePerShare" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PreferredStockParOrStatedValuePerShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Preferred stock, par value</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PreferredStockParOrStatedValuePerShare" xlink:to="us-gaap_PreferredStockParOrStatedValuePerShare_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PreferredStockParOrStatedValuePerShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Preferred Stock Par Or Stated Value Per Share</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PreferredStockSharesAuthorized" xlink:type="locator" xlink:label="us-gaap_PreferredStockSharesAuthorized" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PreferredStockSharesAuthorized_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Preferred stock, shares authorized</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PreferredStockSharesAuthorized" xlink:to="us-gaap_PreferredStockSharesAuthorized_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PreferredStockSharesAuthorized_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Preferred Stock Shares Authorized</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PreferredStockSharesIssued" xlink:type="locator" xlink:label="us-gaap_PreferredStockSharesIssued" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PreferredStockSharesIssued_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Preferred stock, shares issued</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PreferredStockSharesIssued" xlink:to="us-gaap_PreferredStockSharesIssued_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PreferredStockSharesIssued_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Preferred Stock Shares Issued</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PreferredStockSharesOutstanding" xlink:type="locator" xlink:label="us-gaap_PreferredStockSharesOutstanding" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PreferredStockSharesOutstanding_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Preferred stock, shares outstanding</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_PreferredStockSharesOutstanding_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Preferred Stock Shares Outstanding</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockNoParValue" xlink:type="locator" xlink:label="us-gaap_CommonStockNoParValue" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CommonStockNoParValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common stock, par value</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommonStockNoParValue" xlink:to="us-gaap_CommonStockNoParValue_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CommonStockNoParValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock No Par Value</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_CommonStockSharesAuthorized_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common stock, shares authorized</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommonStockSharesAuthorized" xlink:to="us-gaap_CommonStockSharesAuthorized_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CommonStockSharesAuthorized_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock Shares Authorized</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockSharesIssued" xlink:type="locator" xlink:label="us-gaap_CommonStockSharesIssued" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CommonStockSharesIssued_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common stock, shares issued</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_CommonStockSharesIssued_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock Shares Issued</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_CommonStockSharesOutstanding_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common stock, shares outstanding</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_CommonStockSharesOutstanding_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock Shares Outstanding</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementAbstract" xlink:type="locator" xlink:label="us-gaap_IncomeStatementAbstract" />
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    <link:label xml:lang="en-US" xlink:label="us-gaap_StatementTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Statement [Table]</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_StockholdersEquity_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Ending Balance</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_SharesIssued_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Ending Balance, Shares</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockDividendsPerShareDeclared" xlink:type="locator" xlink:label="us-gaap_CommonStockDividendsPerShareDeclared" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CommonStockDividendsPerShareDeclared_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Cash dividend, per common share</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommonStockDividendsPerShareDeclared" xlink:to="us-gaap_CommonStockDividendsPerShareDeclared_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CommonStockDividendsPerShareDeclared_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock Dividends Per Share Declared</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_AmortizationOfInventoryOnStepUpBasisAdjustmentToFairValue" xlink:type="locator" xlink:label="mksi_AmortizationOfInventoryOnStepUpBasisAdjustmentToFairValue" />
    <link:label xml:lang="en-US" xlink:label="mksi_AmortizationOfInventoryOnStepUpBasisAdjustmentToFairValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Amortization of inventory on step up basis adjustment to fair value.</link:label>
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    <link:loc xlink:href="mksi-20211231.xsd#mksi_IncreaseDecreaseCurrentAndNonCurrentAccruedCompensation" xlink:type="locator" xlink:label="mksi_IncreaseDecreaseCurrentAndNonCurrentAccruedCompensation" />
    <link:label xml:lang="en-US" xlink:label="mksi_IncreaseDecreaseCurrentAndNonCurrentAccruedCompensation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Increase Decrease Current And Non Current Accrued Compensation.</link:label>
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    <link:loc xlink:href="mksi-20211231.xsd#mksi_ProceedsFromPaymentsForEmployeeStockAwards" xlink:type="locator" xlink:label="mksi_ProceedsFromPaymentsForEmployeeStockAwards" />
    <link:label xml:lang="en-US" xlink:label="mksi_ProceedsFromPaymentsForEmployeeStockAwards_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Proceeds from payments for employee stock awards.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_ProceedsFromPaymentsForEmployeeStockAwards" xlink:to="mksi_ProceedsFromPaymentsForEmployeeStockAwards_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_CashPaidDuringPeriodForInterestAndIncomeTaxAbstract" xlink:type="locator" xlink:label="mksi_CashPaidDuringPeriodForInterestAndIncomeTaxAbstract" />
    <link:label xml:lang="en-US" xlink:label="mksi_CashPaidDuringPeriodForInterestAndIncomeTaxAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Cash Paid During Period For Interest And Income Tax</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_CashPaidDuringPeriodForInterestAndIncomeTaxAbstract" xlink:to="mksi_CashPaidDuringPeriodForInterestAndIncomeTaxAbstract_lbl" />
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementOfCashFlowsAbstract" xlink:type="locator" xlink:label="us-gaap_StatementOfCashFlowsAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StatementOfCashFlowsAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Statement Of Cash Flows [Abstract]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StatementOfCashFlowsAbstract" xlink:to="us-gaap_StatementOfCashFlowsAbstract_lbl" />
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:type="locator" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Cash flows from operating activities:</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Net Cash Provided By Used In Operating Activities [Abstract]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProfitLoss" xlink:type="locator" xlink:label="us-gaap_ProfitLoss" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ProfitLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Net income</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProfitLoss" xlink:to="us-gaap_ProfitLoss_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ProfitLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Profit Loss</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:type="locator" xlink:label="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Adjustments to reconcile net income to net cash provided by operating activities:</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Adjustments To Reconcile Net Income Loss To Cash Provided By Used In Operating Activities [Abstract]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DepreciationAndAmortization" xlink:type="locator" xlink:label="us-gaap_DepreciationAndAmortization" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DepreciationAndAmortization_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Depreciation and amortization</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DepreciationAndAmortization" xlink:to="us-gaap_DepreciationAndAmortization_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DepreciationAndAmortization_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Depreciation And Amortization</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_UnrealizedGainLossOnDerivatives" xlink:type="locator" xlink:label="us-gaap_UnrealizedGainLossOnDerivatives" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_UnrealizedGainLossOnDerivatives_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Unrealized (gain) loss on derivatives not designated as hedging instruments</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_UnrealizedGainLossOnDerivatives" xlink:to="us-gaap_UnrealizedGainLossOnDerivatives_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_UnrealizedGainLossOnDerivatives_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Unrealized Gain Loss On Derivatives</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_AmortizationOfInventoryOnStepUpBasisAdjustmentToFairValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Amortization of inventory step-up adjustment to fair value</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_AmortizationOfInventoryOnStepUpBasisAdjustmentToFairValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Amortization Of Inventory On Step Up Basis Adjustment To Fair Value</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AmortizationOfFinancingCostsAndDiscounts" xlink:type="locator" xlink:label="us-gaap_AmortizationOfFinancingCostsAndDiscounts" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AmortizationOfFinancingCostsAndDiscounts_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Amortization of debt issuance costs and original issue discount</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AmortizationOfFinancingCostsAndDiscounts" xlink:to="us-gaap_AmortizationOfFinancingCostsAndDiscounts_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AmortizationOfFinancingCostsAndDiscounts_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Amortization Of Financing Costs And Discounts</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensation" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensation" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Stock-based compensation</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensation" xlink:to="us-gaap_ShareBasedCompensation_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InventoryWriteDown" xlink:type="locator" xlink:label="us-gaap_InventoryWriteDown" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_InventoryWriteDown_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Provision for excess and obsolete inventory</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InventoryWriteDown" xlink:to="us-gaap_InventoryWriteDown_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_InventoryWriteDown_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Inventory Write Down</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredIncomeTaxExpenseBenefit" xlink:type="locator" xlink:label="us-gaap_DeferredIncomeTaxExpenseBenefit" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredIncomeTaxExpenseBenefit_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Deferred income taxes</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredIncomeTaxExpenseBenefit" xlink:to="us-gaap_DeferredIncomeTaxExpenseBenefit_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredIncomeTaxExpenseBenefit_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Income Tax Expense Benefit</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherNoncashIncomeExpense" xlink:type="locator" xlink:label="us-gaap_OtherNoncashIncomeExpense" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OtherNoncashIncomeExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Other</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherNoncashIncomeExpense" xlink:to="us-gaap_OtherNoncashIncomeExpense_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OtherNoncashIncomeExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Other Noncash Income Expense</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Changes in operating assets and liabilities, net of businesses acquired:</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" xlink:to="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Increase Decrease In Operating Capital [Abstract]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsReceivable" xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInAccountsReceivable" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncreaseDecreaseInAccountsReceivable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Trade accounts receivable</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_IncreaseDecreaseInAccountsReceivable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Increase Decrease In Accounts Receivable</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncreaseDecreaseInInventories" xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInInventories" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncreaseDecreaseInInventories_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Inventories</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncreaseDecreaseInInventories" xlink:to="us-gaap_IncreaseDecreaseInInventories_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncreaseDecreaseInInventories_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Increase Decrease In Inventories</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncreaseDecreaseInIncomeTaxesPayableNetOfIncomeTaxesReceivable" xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInIncomeTaxesPayableNetOfIncomeTaxesReceivable" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncreaseDecreaseInIncomeTaxesPayableNetOfIncomeTaxesReceivable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Income taxes payable</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_IncreaseDecreaseInIncomeTaxesPayableNetOfIncomeTaxesReceivable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Increase Decrease In Income Taxes Payable Net Of Income Taxes Receivable</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncreaseDecreaseInOtherOperatingAssets" xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInOtherOperatingAssets" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncreaseDecreaseInOtherOperatingAssets_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Other current and non-current assets</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_IncreaseDecreaseInOtherOperatingAssets_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Increase Decrease In Other Operating Assets</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_IncreaseDecreaseCurrentAndNonCurrentAccruedCompensation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Current and non-current accrued compensation</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_IncreaseDecreaseCurrentAndNonCurrentAccruedCompensation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Increase Decrease Current And Non Current Accrued Compensation</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncreaseDecreaseInOtherOperatingLiabilities" xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInOtherOperatingLiabilities" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncreaseDecreaseInOtherOperatingLiabilities_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other current and non-current liabilities</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_IncreaseDecreaseInOtherOperatingLiabilities_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Increase Decrease In Other Operating Liabilities</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsPayableTrade" xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInAccountsPayableTrade" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncreaseDecreaseInAccountsPayableTrade_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accounts payable</link:label>
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    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:type="locator" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" />
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    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired" xlink:type="locator" xlink:label="us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired" />
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    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PaymentsToAcquireAvailableForSaleSecuritiesDebt" xlink:type="locator" xlink:label="us-gaap_PaymentsToAcquireAvailableForSaleSecuritiesDebt" />
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    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities" xlink:type="locator" xlink:label="us-gaap_ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities" />
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    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProceedsFromSaleOfAvailableForSaleSecuritiesDebt" xlink:type="locator" xlink:label="us-gaap_ProceedsFromSaleOfAvailableForSaleSecuritiesDebt" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ProceedsFromSaleOfAvailableForSaleSecuritiesDebt_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Sales of investments</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProceedsFromSaleOfAvailableForSaleSecuritiesDebt" xlink:to="us-gaap_ProceedsFromSaleOfAvailableForSaleSecuritiesDebt_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ProceedsFromSaleOfAvailableForSaleSecuritiesDebt_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Proceeds From Sale Of Available For Sale Securities Debt</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment" xlink:type="locator" xlink:label="us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Proceeds from sale of assets</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment" xlink:to="us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment_lbl" />
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    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:type="locator" xlink:label="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" />
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    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:to="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_lbl" />
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    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:type="locator" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivities" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivities_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Net cash used in investing activities</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:to="us-gaap_NetCashProvidedByUsedInInvestingActivities_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivities_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Net Cash Provided By Used In Investing Activities</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:type="locator" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Cash flows from financing activities:</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Net Cash Provided By Used In Financing Activities [Abstract]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProceedsFromBankDebt" xlink:type="locator" xlink:label="us-gaap_ProceedsFromBankDebt" />
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    <link:label xml:lang="en-US" xlink:label="us-gaap_RepaymentsOfDebt_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Repayments Of Debt</link:label>
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    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PaymentsOfDividendsCommonStock" xlink:type="locator" xlink:label="us-gaap_PaymentsOfDividendsCommonStock" />
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    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations" xlink:type="locator" xlink:label="us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations" />
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    <link:loc xlink:href="mksi-20211231.xsd#mksi_CashAndCashEquivalentsAndInvestmentsPolicyTextBlock" xlink:type="locator" xlink:label="mksi_CashAndCashEquivalentsAndInvestmentsPolicyTextBlock" />
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    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GoodwillAndIntangibleAssetsIntangibleAssetsPolicy" xlink:type="locator" xlink:label="us-gaap_GoodwillAndIntangibleAssetsIntangibleAssetsPolicy" />
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    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GoodwillAndIntangibleAssetsGoodwillPolicy" xlink:type="locator" xlink:label="us-gaap_GoodwillAndIntangibleAssetsGoodwillPolicy" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_GoodwillAndIntangibleAssetsGoodwillPolicy_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Goodwill</link:label>
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    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ImpairmentOrDisposalOfLongLivedAssetsPolicyTextBlock" xlink:type="locator" xlink:label="us-gaap_ImpairmentOrDisposalOfLongLivedAssetsPolicyTextBlock" />
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    <link:loc xlink:href="mksi-20211231.xsd#mksi_ScheduleOfAllocationOfPurchasePriceTableTextBlock" xlink:type="locator" xlink:label="mksi_ScheduleOfAllocationOfPurchasePriceTableTextBlock" />
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    <link:loc xlink:href="mksi-20211231.xsd#mksi_ElectroScientificIndustriesIncMember" xlink:type="locator" xlink:label="mksi_ElectroScientificIndustriesIncMember" />
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    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTextBlock" xlink:type="locator" xlink:label="us-gaap_ScheduleOfRestructuringAndRelatedCostsTextBlock" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfRestructuringAndRelatedCostsTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule of Company&apos;s Restructuring Activity</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfRestructuringAndRelatedCostsTextBlock" xlink:to="us-gaap_ScheduleOfRestructuringAndRelatedCostsTextBlock_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfRestructuringAndRelatedCostsTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Restructuring And Related Costs [Text Block]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_RevenueRecognitionPaymentTerms" xlink:type="locator" xlink:label="mksi_RevenueRecognitionPaymentTerms" />
    <link:label xml:lang="en-US" xlink:label="mksi_RevenueRecognitionPaymentTerms_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Revenue recognition payment terms.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_RevenueRecognitionPaymentTerms" xlink:to="mksi_RevenueRecognitionPaymentTerms_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_ScheduleOfSignificantAccountingPoliciesLineItems" xlink:type="locator" xlink:label="mksi_ScheduleOfSignificantAccountingPoliciesLineItems" />
    <link:label xml:lang="en-US" xlink:label="mksi_ScheduleOfSignificantAccountingPoliciesLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Schedule of significant accounting policies [Line Items].</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_ScheduleOfSignificantAccountingPoliciesLineItems" xlink:to="mksi_ScheduleOfSignificantAccountingPoliciesLineItems_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_ScheduleOfSignificantAccountingPoliciesTable" xlink:type="locator" xlink:label="mksi_ScheduleOfSignificantAccountingPoliciesTable" />
    <link:label xml:lang="en-US" xlink:label="mksi_ScheduleOfSignificantAccountingPoliciesTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Schedule of significant accounting policies [Table].</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_ScheduleOfSignificantAccountingPoliciesTable" xlink:to="mksi_ScheduleOfSignificantAccountingPoliciesTable_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_ScheduleOfSignificantAccountingPoliciesTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule Of Significant Accounting Policies [Table]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_ScheduleOfSignificantAccountingPoliciesTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Significant Accounting Policies [Table]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeAxis" xlink:type="locator" xlink:label="srt_RangeAxis" />
    <link:label xml:lang="en-US" xlink:label="srt_RangeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Statistical Measurement</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_RangeAxis" xlink:to="srt_RangeAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="srt_RangeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Range [Axis]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember" xlink:type="locator" xlink:label="srt_RangeMember" />
    <link:label xml:lang="en-US" xlink:label="srt_RangeMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Statistical Measurement</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_RangeMember" xlink:to="srt_RangeMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="srt_RangeMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Range [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MinimumMember" xlink:type="locator" xlink:label="srt_MinimumMember" />
    <link:label xml:lang="en-US" xlink:label="srt_MinimumMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Minimum [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_MinimumMember" xlink:to="srt_MinimumMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="srt_MinimumMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Minimum [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MaximumMember" xlink:type="locator" xlink:label="srt_MaximumMember" />
    <link:label xml:lang="en-US" xlink:label="srt_MaximumMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Maximum [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_MaximumMember" xlink:to="srt_MaximumMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="srt_MaximumMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Maximum [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:type="locator" xlink:label="us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accounting Standards Update</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:to="us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Adjustments For New Accounting Pronouncements [Axis]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:type="locator" xlink:label="us-gaap_TypeOfAdoptionMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TypeOfAdoptionMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accounting Standards Update</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TypeOfAdoptionMember" xlink:to="us-gaap_TypeOfAdoptionMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TypeOfAdoptionMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Type Of Adoption [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccountingStandardsUpdate201409Member" xlink:type="locator" xlink:label="us-gaap_AccountingStandardsUpdate201409Member" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AccountingStandardsUpdate201409Member_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accounting Standards Codification Topic 606 adjustment [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccountingStandardsUpdate201409Member" xlink:to="us-gaap_AccountingStandardsUpdate201409Member_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AccountingStandardsUpdate201409Member_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Accounting Standards Update201409 [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ConcentrationRiskByTypeAxis" xlink:type="locator" xlink:label="us-gaap_ConcentrationRiskByTypeAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ConcentrationRiskByTypeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Concentration Risk Type</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ConcentrationRiskByTypeAxis" xlink:to="us-gaap_ConcentrationRiskByTypeAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ConcentrationRiskByTypeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Concentration Risk By Type [Axis]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:type="locator" xlink:label="us-gaap_ConcentrationRiskTypeDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ConcentrationRiskTypeDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Concentration Risk Type</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ConcentrationRiskTypeDomain" xlink:to="us-gaap_ConcentrationRiskTypeDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ConcentrationRiskTypeDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Concentration Risk Type [Domain]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CustomerConcentrationRiskMember" xlink:type="locator" xlink:label="us-gaap_CustomerConcentrationRiskMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CustomerConcentrationRiskMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Customer Concentration Risk [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CustomerConcentrationRiskMember" xlink:to="us-gaap_CustomerConcentrationRiskMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CustomerConcentrationRiskMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Customer Concentration Risk [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MajorCustomersAxis" xlink:type="locator" xlink:label="srt_MajorCustomersAxis" />
    <link:label xml:lang="en-US" xlink:label="srt_MajorCustomersAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Customer</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_MajorCustomersAxis" xlink:to="srt_MajorCustomersAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="srt_MajorCustomersAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Major Customers [Axis]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_NameOfMajorCustomerDomain" xlink:type="locator" xlink:label="srt_NameOfMajorCustomerDomain" />
    <link:label xml:lang="en-US" xlink:label="srt_NameOfMajorCustomerDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Customer</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_NameOfMajorCustomerDomain" xlink:to="srt_NameOfMajorCustomerDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="srt_NameOfMajorCustomerDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Name Of Major Customer [Domain]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_SemiconductorProductsMember" xlink:type="locator" xlink:label="mksi_SemiconductorProductsMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_SemiconductorProductsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Semiconductor products [Member].</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_SemiconductorProductsMember" xlink:to="mksi_SemiconductorProductsMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_SemiconductorProductsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Semiconductor Products [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_SemiconductorProductsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Semiconductor Products [Member]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_OneCustomerMember" xlink:type="locator" xlink:label="mksi_OneCustomerMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_OneCustomerMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">One customer.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_OneCustomerMember" xlink:to="mksi_OneCustomerMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_OneCustomerMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">One Customer [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_OneCustomerMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">One Customer [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:type="locator" xlink:label="us-gaap_ConcentrationRiskByBenchmarkAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ConcentrationRiskByBenchmarkAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Concentration Risk Benchmark</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:to="us-gaap_ConcentrationRiskByBenchmarkAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ConcentrationRiskByBenchmarkAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Concentration Risk By Benchmark [Axis]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:type="locator" xlink:label="us-gaap_ConcentrationRiskBenchmarkDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ConcentrationRiskBenchmarkDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Concentration Risk Benchmark</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ConcentrationRiskBenchmarkDomain" xlink:to="us-gaap_ConcentrationRiskBenchmarkDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ConcentrationRiskBenchmarkDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Concentration Risk Benchmark [Domain]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SalesRevenueNetMember" xlink:type="locator" xlink:label="us-gaap_SalesRevenueNetMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SalesRevenueNetMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Sales Revenue, Net [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SalesRevenueNetMember" xlink:to="us-gaap_SalesRevenueNetMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SalesRevenueNetMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Sales Revenue Net [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccountsReceivableMember" xlink:type="locator" xlink:label="us-gaap_AccountsReceivableMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AccountsReceivableMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accounts Receivable [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccountsReceivableMember" xlink:to="us-gaap_AccountsReceivableMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AccountsReceivableMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Accounts Receivable [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentByTypeAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PropertyPlantAndEquipmentByTypeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Long-Lived Tangible Asset</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:to="us-gaap_PropertyPlantAndEquipmentByTypeAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PropertyPlantAndEquipmentByTypeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Property Plant And Equipment By Type [Axis]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentTypeDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PropertyPlantAndEquipmentTypeDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Long-Lived Tangible Asset</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="us-gaap_PropertyPlantAndEquipmentTypeDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PropertyPlantAndEquipmentTypeDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Property Plant And Equipment Type [Domain]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BuildingMember" xlink:type="locator" xlink:label="us-gaap_BuildingMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_BuildingMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Building [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BuildingMember" xlink:to="us-gaap_BuildingMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_BuildingMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Building [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_MachineryAndEquipmentMember" xlink:type="locator" xlink:label="us-gaap_MachineryAndEquipmentMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_MachineryAndEquipmentMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Machinery and Equipment [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_MachineryAndEquipmentMember" xlink:to="us-gaap_MachineryAndEquipmentMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_MachineryAndEquipmentMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Machinery And Equipment [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FurnitureAndFixturesMember" xlink:type="locator" xlink:label="us-gaap_FurnitureAndFixturesMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FurnitureAndFixturesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Furniture and Fixtures [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FurnitureAndFixturesMember" xlink:to="us-gaap_FurnitureAndFixturesMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FurnitureAndFixturesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Furniture And Fixtures [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OfficeEquipmentMember" xlink:type="locator" xlink:label="us-gaap_OfficeEquipmentMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OfficeEquipmentMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Office Equipment [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OfficeEquipmentMember" xlink:to="us-gaap_OfficeEquipmentMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OfficeEquipmentMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Office Equipment [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:type="locator" xlink:label="us-gaap_IncomeStatementLocationAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeStatementLocationAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Income Statement Location</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeStatementLocationAxis" xlink:to="us-gaap_IncomeStatementLocationAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeStatementLocationAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Income Statement Location [Axis]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:type="locator" xlink:label="us-gaap_IncomeStatementLocationDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeStatementLocationDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Income Statement Location</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeStatementLocationDomain" xlink:to="us-gaap_IncomeStatementLocationDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeStatementLocationDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Income Statement Location [Domain]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherExpenseMember" xlink:type="locator" xlink:label="us-gaap_OtherExpenseMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OtherExpenseMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other Expense [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherExpenseMember" xlink:to="us-gaap_OtherExpenseMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OtherExpenseMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Other Expense [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_ScheduleOfSignificantAccountingPoliciesLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule Of Significant Accounting Policies [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_ScheduleOfSignificantAccountingPoliciesLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Significant Accounting Policies [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_RevenueRecognitionPaymentTerms_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Company&apos;s normal payment terms</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_RevenueRecognitionPaymentTerms_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Revenue Recognition Payment Terms</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_WarrantyPeriod" xlink:type="locator" xlink:label="mksi_WarrantyPeriod" />
    <link:label xml:lang="en-US" xlink:label="mksi_WarrantyPeriod_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Warranty period.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_WarrantyPeriod" xlink:to="mksi_WarrantyPeriod_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_SeparatelyPricedContractsTerm" xlink:type="locator" xlink:label="mksi_SeparatelyPricedContractsTerm" />
    <link:label xml:lang="en-US" xlink:label="mksi_SeparatelyPricedContractsTerm_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Separately priced contracts term.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_SeparatelyPricedContractsTerm" xlink:to="mksi_SeparatelyPricedContractsTerm_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_WarrantyPeriod_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Warranty period</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_WarrantyPeriod_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Warranty Period</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_SeparatelyPricedContractsTerm_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Term of separately priced contracts</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_SeparatelyPricedContractsTerm_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Separately Priced Contracts Term</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationOptionalExemptionRemainingDuration" xlink:type="locator" xlink:label="us-gaap_RevenueRemainingPerformanceObligationOptionalExemptionRemainingDuration" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RevenueRemainingPerformanceObligationOptionalExemptionRemainingDuration_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Remaining performance obligation period</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RevenueRemainingPerformanceObligationOptionalExemptionRemainingDuration" xlink:to="us-gaap_RevenueRemainingPerformanceObligationOptionalExemptionRemainingDuration_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RevenueRemainingPerformanceObligationOptionalExemptionRemainingDuration_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Revenue Remaining Performance Obligation Optional Exemption Remaining Duration</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_MinimumPeriodOfCompanysResearchAndDevelopmentProjects" xlink:type="locator" xlink:label="mksi_MinimumPeriodOfCompanysResearchAndDevelopmentProjects" />
    <link:label xml:lang="en-US" xlink:label="mksi_MinimumPeriodOfCompanysResearchAndDevelopmentProjects_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Minimum period of company&apos;s research and development projects.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_MinimumPeriodOfCompanysResearchAndDevelopmentProjects" xlink:to="mksi_MinimumPeriodOfCompanysResearchAndDevelopmentProjects_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_MaximumPeriodOfCompanysResearchAndDevelopmentProjects" xlink:type="locator" xlink:label="mksi_MaximumPeriodOfCompanysResearchAndDevelopmentProjects" />
    <link:label xml:lang="en-US" xlink:label="mksi_MaximumPeriodOfCompanysResearchAndDevelopmentProjects_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Maximum period of company&apos;s research and development projects.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_MaximumPeriodOfCompanysResearchAndDevelopmentProjects" xlink:to="mksi_MaximumPeriodOfCompanysResearchAndDevelopmentProjects_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_MinimumPeriodOfCompanysResearchAndDevelopmentProjects_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Minimum period of company&apos;s research and development projects</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_MinimumPeriodOfCompanysResearchAndDevelopmentProjects_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Minimum Period Of Companys Research And Development Projects</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_MaximumPeriodOfCompanysResearchAndDevelopmentProjects_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Maximum period of company&apos;s research and development projects</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_MaximumPeriodOfCompanysResearchAndDevelopmentProjects_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Maximum Period Of Companys Research And Development Projects</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Vesting period</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Award Vesting Period1</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_NumberOfCustomersAccountedForTenOrMorePercentOfAccountsReceivable" xlink:type="locator" xlink:label="mksi_NumberOfCustomersAccountedForTenOrMorePercentOfAccountsReceivable" />
    <link:label xml:lang="en-US" xlink:label="mksi_NumberOfCustomersAccountedForTenOrMorePercentOfAccountsReceivable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Number of customers accounted for ten or more percent of accounts receivable.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_NumberOfCustomersAccountedForTenOrMorePercentOfAccountsReceivable" xlink:to="mksi_NumberOfCustomersAccountedForTenOrMorePercentOfAccountsReceivable_lbl" />
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ConcentrationRiskPercentage1" xlink:type="locator" xlink:label="us-gaap_ConcentrationRiskPercentage1" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ConcentrationRiskPercentage1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Concentration risk, percentage</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ConcentrationRiskPercentage1" xlink:to="us-gaap_ConcentrationRiskPercentage1_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ConcentrationRiskPercentage1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Concentration Risk Percentage1</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_NumberOfCustomersAccountedForTenOrMorePercentOfAccountsReceivable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Number of customers accounted for approximately 18% of total accounts receivable</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_NumberOfCustomersAccountedForTenOrMorePercentOfAccountsReceivable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Number Of Customers Accounted For Ten Or More Percent Of Accounts Receivable</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_AmortizationPeriodOfLeaseholdImprovements" xlink:type="locator" xlink:label="mksi_AmortizationPeriodOfLeaseholdImprovements" />
    <link:label xml:lang="en-US" xlink:label="mksi_AmortizationPeriodOfLeaseholdImprovements_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Amortization period of leasehold improvements.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_AmortizationPeriodOfLeaseholdImprovements" xlink:to="mksi_AmortizationPeriodOfLeaseholdImprovements_lbl" />
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife" xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentUsefulLife" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PropertyPlantAndEquipmentUsefulLife_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Estimated useful lives</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PropertyPlantAndEquipmentUsefulLife" xlink:to="us-gaap_PropertyPlantAndEquipmentUsefulLife_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PropertyPlantAndEquipmentUsefulLife_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Property Plant And Equipment Useful Life</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_AmortizationPeriodOfLeaseholdImprovements_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Amortization period of leasehold improvements</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_AmortizationPeriodOfLeaseholdImprovements_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Amortization Period Of Leasehold Improvements</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife" xlink:type="locator" xlink:label="us-gaap_FiniteLivedIntangibleAssetUsefulLife" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetUsefulLife_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Intangible assets amortized period</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetUsefulLife" xlink:to="us-gaap_FiniteLivedIntangibleAssetUsefulLife_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetUsefulLife_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finite Lived Intangible Asset Useful Life</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ForeignCurrencyTransactionGainLossRealized" xlink:type="locator" xlink:label="us-gaap_ForeignCurrencyTransactionGainLossRealized" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ForeignCurrencyTransactionGainLossRealized_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Net foreign exchange losses from re-measurement</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ForeignCurrencyTransactionGainLossRealized" xlink:to="us-gaap_ForeignCurrencyTransactionGainLossRealized_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ForeignCurrencyTransactionGainLossRealized_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Foreign Currency Transaction Gain Loss Realized</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_MinimumPercentageOfRecognizedTaxBenefitsFromUncertainTaxPosition" xlink:type="locator" xlink:label="mksi_MinimumPercentageOfRecognizedTaxBenefitsFromUncertainTaxPosition" />
    <link:label xml:lang="en-US" xlink:label="mksi_MinimumPercentageOfRecognizedTaxBenefitsFromUncertainTaxPosition_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Minimum percentage of recognized tax benefits from uncertain tax position.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_MinimumPercentageOfRecognizedTaxBenefitsFromUncertainTaxPosition" xlink:to="mksi_MinimumPercentageOfRecognizedTaxBenefitsFromUncertainTaxPosition_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_MinimumPercentageOfRecognizedTaxBenefitsFromUncertainTaxPosition_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Minimum percentage of recognition of tax benefits from uncertain tax positions</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_MinimumPercentageOfRecognizedTaxBenefitsFromUncertainTaxPosition_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Minimum Percentage Of Recognized Tax Benefits From Uncertain Tax Position</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_BusinessAcquisitionDateOfCompletion" xlink:type="locator" xlink:label="mksi_BusinessAcquisitionDateOfCompletion" />
    <link:label xml:lang="en-US" xlink:label="mksi_BusinessAcquisitionDateOfCompletion_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Business acquisition date of completion.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_BusinessAcquisitionDateOfCompletion" xlink:to="mksi_BusinessAcquisitionDateOfCompletion_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_BusinessCombinationPricePerShareOfCommonStockInCash" xlink:type="locator" xlink:label="mksi_BusinessCombinationPricePerShareOfCommonStockInCash" />
    <link:label xml:lang="en-US" xlink:label="mksi_BusinessCombinationPricePerShareOfCommonStockInCash_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Business combination, price per share of common stock in cash.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_BusinessCombinationPricePerShareOfCommonStockInCash" xlink:to="mksi_BusinessCombinationPricePerShareOfCommonStockInCash_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_BusinessAcquisitionDateOfCompletion_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Date of completed previously announced acquisition</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_BusinessAcquisitionDateOfCompletion_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Business Acquisition Date Of Completion</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_BusinessCombinationPricePerShareOfCommonStockInCash_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Price per share of common stock in cash</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_BusinessCombinationPricePerShareOfCommonStockInCash_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Business Combination Price Per Share Of Common Stock In Cash</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_BusinessCombinationCashPaidInSettlementOfShareBasedCompensationAwards" xlink:type="locator" xlink:label="mksi_BusinessCombinationCashPaidInSettlementOfShareBasedCompensationAwards" />
    <link:label xml:lang="en-US" xlink:label="mksi_BusinessCombinationCashPaidInSettlementOfShareBasedCompensationAwards_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Business combination cash paid in settlement of share based compensation awards.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_BusinessCombinationCashPaidInSettlementOfShareBasedCompensationAwards" xlink:to="mksi_BusinessCombinationCashPaidInSettlementOfShareBasedCompensationAwards_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_BusinessCombinationCashPaidForOutstandingShares_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Cash paid for outstanding shares</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_BusinessCombinationCashPaidForOutstandingShares_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Business Combination Cash Paid For Outstanding Shares</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_BusinessCombinationCashPaidInSettlementOfShareBasedCompensationAwards_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Settlement of share-based compensation awards</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Finite-Lived Intangible Assets, Major Class Name</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finite Lived Intangible Assets Major Class Name [Domain]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_CompletedTechnologyRightsMember" xlink:type="locator" xlink:label="mksi_CompletedTechnologyRightsMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_CompletedTechnologyRightsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Completed Technology Rights [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_CompletedTechnologyRightsMember" xlink:to="mksi_CompletedTechnologyRightsMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_CompletedTechnologyRightsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Completed Technology [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_CompletedTechnologyRightsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Completed Technology Rights [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CustomerRelationshipsMember" xlink:type="locator" xlink:label="us-gaap_CustomerRelationshipsMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CustomerRelationshipsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Customer Relationships [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CustomerRelationshipsMember" xlink:to="us-gaap_CustomerRelationshipsMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CustomerRelationshipsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Customer Relationships [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TradeNamesMember" xlink:type="locator" xlink:label="us-gaap_TradeNamesMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TradeNamesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Trade Names [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TradeNamesMember" xlink:to="us-gaap_TradeNamesMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TradeNamesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Trade Names [Member]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_BacklogMember" xlink:type="locator" xlink:label="mksi_BacklogMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_BacklogMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Backlog [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_BacklogMember" xlink:to="mksi_BacklogMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_BacklogMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Backlog [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_BacklogMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Backlog [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TrademarksAndTradeNamesMember" xlink:type="locator" xlink:label="us-gaap_TrademarksAndTradeNamesMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TrademarksAndTradeNamesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Trademarks and Trade Names [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TrademarksAndTradeNamesMember" xlink:to="us-gaap_TrademarksAndTradeNamesMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TrademarksAndTradeNamesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Trademarks And Trade Names [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:type="locator" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StatementBusinessSegmentsAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Segments</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_StatementBusinessSegmentsAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StatementBusinessSegmentsAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Statement Business Segments [Axis]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SegmentDomain" xlink:type="locator" xlink:label="us-gaap_SegmentDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SegmentDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Segments</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SegmentDomain" xlink:to="us-gaap_SegmentDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SegmentDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Segment [Domain]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_LaserProductsMember" xlink:type="locator" xlink:label="mksi_LaserProductsMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_LaserProductsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Laser products.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_LaserProductsMember" xlink:to="mksi_LaserProductsMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_LaserProductsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Lasers Products [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_LaserProductsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Laser Products [Member]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_NonLaserProductsMember" xlink:type="locator" xlink:label="mksi_NonLaserProductsMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_NonLaserProductsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Non Laser Products [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_NonLaserProductsMember" xlink:to="mksi_NonLaserProductsMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_NonLaserProductsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Non Laser Products [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_NonLaserProductsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Non Laser Products [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems" xlink:type="locator" xlink:label="us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Acquired Finite Lived Intangible Assets [Line Items]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems" xlink:to="us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Acquired Finite Lived Intangible Assets [Line Items]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinitelivedIntangibleAssetsAcquired1" xlink:type="locator" xlink:label="us-gaap_FinitelivedIntangibleAssetsAcquired1" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FinitelivedIntangibleAssetsAcquired1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Acquired intangible assets, purchase price</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FinitelivedIntangibleAssetsAcquired1" xlink:to="us-gaap_FinitelivedIntangibleAssetsAcquired1_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FinitelivedIntangibleAssetsAcquired1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finitelived Intangible Assets Acquired1</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetUsefulLife_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Acquired intangible assets, estimated useful lives</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_FairValueWriteupOfAcquiredFinishedGoodsInventory" xlink:type="locator" xlink:label="mksi_FairValueWriteupOfAcquiredFinishedGoodsInventory" />
    <link:label xml:lang="en-US" xlink:label="mksi_FairValueWriteupOfAcquiredFinishedGoodsInventory_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Fair value write-up of acquired finished goods inventory.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_FairValueWriteupOfAcquiredFinishedGoodsInventory" xlink:to="mksi_FairValueWriteupOfAcquiredFinishedGoodsInventory_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_IncrementalCostOfSalesCharge" xlink:type="locator" xlink:label="mksi_IncrementalCostOfSalesCharge" />
    <link:label xml:lang="en-US" xlink:label="mksi_IncrementalCostOfSalesCharge_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Incremental cost of sales charge.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_IncrementalCostOfSalesCharge" xlink:to="mksi_IncrementalCostOfSalesCharge_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_FairValueWriteupOfAcquiredFinishedGoodsInventory_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Fair value write-up of acquired finished goods inventory</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_FairValueWriteupOfAcquiredFinishedGoodsInventory_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Fair Value Writeup Of Acquired Finished Goods Inventory</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_IncrementalCostOfSalesCharge_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Incremental costs of sales charge</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_IncrementalCostOfSalesCharge_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Incremental Cost Of Sales Charge</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_IncreaseOfAcquiredPropertyPlantAndEquipmentExcludingTheFairValueWriteUp" xlink:type="locator" xlink:label="mksi_IncreaseOfAcquiredPropertyPlantAndEquipmentExcludingTheFairValueWriteUp" />
    <link:label xml:lang="en-US" xlink:label="mksi_IncreaseOfAcquiredPropertyPlantAndEquipmentExcludingTheFairValueWriteUp_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Increase of acquired property plant and equipment excluding the fair value write up.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_IncreaseOfAcquiredPropertyPlantAndEquipmentExcludingTheFairValueWriteUp" xlink:to="mksi_IncreaseOfAcquiredPropertyPlantAndEquipmentExcludingTheFairValueWriteUp_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_IncreaseOfAcquiredPropertyPlantAndEquipmentExcludingTheFairValueWriteUp_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Fair value excluding write-up of acquired property, plant and equipment</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_IncreaseOfAcquiredPropertyPlantAndEquipmentExcludingTheFairValueWriteUp_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Increase Of Acquired Property Plant And Equipment Excluding The Fair Value Write Up</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_BusinessCombinationCompensationExpenses" xlink:type="locator" xlink:label="mksi_BusinessCombinationCompensationExpenses" />
    <link:label xml:lang="en-US" xlink:label="mksi_BusinessCombinationCompensationExpenses_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Business combination compensation expenses.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_BusinessCombinationCompensationExpenses" xlink:to="mksi_BusinessCombinationCompensationExpenses_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_BusinessCombinationCompensationExpenses_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Compensation expense</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_BusinessCombinationCompensationExpenses_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Business Combination Compensation Expenses</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense" xlink:type="locator" xlink:label="us-gaap_AllocatedShareBasedCompensationExpense" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AllocatedShareBasedCompensationExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Stock-based compensation expense</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AllocatedShareBasedCompensationExpense" xlink:to="us-gaap_AllocatedShareBasedCompensationExpense_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AllocatedShareBasedCompensationExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Allocated Share Based Compensation Expense</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_BusinessAcquisitionEarningsPerShareBasic" xlink:type="locator" xlink:label="mksi_BusinessAcquisitionEarningsPerShareBasic" />
    <link:label xml:lang="en-US" xlink:label="mksi_BusinessAcquisitionEarningsPerShareBasic_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Business acquisition earnings per share basic.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_BusinessAcquisitionEarningsPerShareBasic" xlink:to="mksi_BusinessAcquisitionEarningsPerShareBasic_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_BusinessAcquisitionEarningsPerShareDiluted" xlink:type="locator" xlink:label="mksi_BusinessAcquisitionEarningsPerShareDiluted" />
    <link:label xml:lang="en-US" xlink:label="mksi_BusinessAcquisitionEarningsPerShareDiluted_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Business acquisition earnings per share diluted.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_BusinessAcquisitionEarningsPerShareDiluted" xlink:to="mksi_BusinessAcquisitionEarningsPerShareDiluted_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_BusinessAcquisitionEarningsPerShareAbstract" xlink:type="locator" xlink:label="mksi_BusinessAcquisitionEarningsPerShareAbstract" />
    <link:label xml:lang="en-US" xlink:label="mksi_BusinessAcquisitionEarningsPerShareAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Business acquisition earnings per share.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_BusinessAcquisitionEarningsPerShareAbstract" xlink:to="mksi_BusinessAcquisitionEarningsPerShareAbstract_lbl" />
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessAcquisitionProFormaInformationAbstract" xlink:type="locator" xlink:label="us-gaap_BusinessAcquisitionProFormaInformationAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_BusinessAcquisitionProFormaInformationAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Business Acquisition Pro Forma Information [Abstract]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BusinessAcquisitionProFormaInformationAbstract" xlink:to="us-gaap_BusinessAcquisitionProFormaInformationAbstract_lbl" />
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual" xlink:type="locator" xlink:label="us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Total net revenues</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual" xlink:to="us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Business Combination Pro Forma Information Revenue Of Acquiree Since Acquisition Date Actual</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual" xlink:type="locator" xlink:label="us-gaap_BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Net loss</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual" xlink:to="us-gaap_BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Business Combination Pro Forma Information Earnings Or Loss Of Acquiree Since Acquisition Date Actual</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_BusinessAcquisitionEarningsPerShareAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Net loss per share:</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_BusinessAcquisitionEarningsPerShareAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Business Acquisition Earnings Per Share [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_BusinessAcquisitionEarningsPerShareBasic_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Basic</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_BusinessAcquisitionEarningsPerShareBasic_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Business Acquisition Earnings Per Share Basic</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_BusinessAcquisitionEarningsPerShareDiluted_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Diluted</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_BusinessAcquisitionEarningsPerShareDiluted_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Business Acquisition Earnings Per Share Diluted</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_BusinessAcquisitionProFormaEarningsPerShareAbstract" xlink:type="locator" xlink:label="mksi_BusinessAcquisitionProFormaEarningsPerShareAbstract" />
    <link:label xml:lang="en-US" xlink:label="mksi_BusinessAcquisitionProFormaEarningsPerShareAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Business Acquisition Pro Forma Earnings Per Share [Abstract]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_BusinessAcquisitionProFormaEarningsPerShareAbstract" xlink:to="mksi_BusinessAcquisitionProFormaEarningsPerShareAbstract_lbl" />
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessAcquisitionsProFormaRevenue" xlink:type="locator" xlink:label="us-gaap_BusinessAcquisitionsProFormaRevenue" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_BusinessAcquisitionsProFormaRevenue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Total net revenues</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BusinessAcquisitionsProFormaRevenue" xlink:to="us-gaap_BusinessAcquisitionsProFormaRevenue_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_BusinessAcquisitionsProFormaRevenue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Business Acquisitions Pro Forma Revenue</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss" xlink:type="locator" xlink:label="us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Net income</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss" xlink:to="us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Business Acquisitions Pro Forma Net Income Loss</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_BusinessAcquisitionProFormaEarningsPerShareAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Net income per share:</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_BusinessAcquisitionProFormaEarningsPerShareAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Business Acquisition Pro Forma Earnings Per Share [Abstract]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessAcquisitionProFormaEarningsPerShareBasic" xlink:type="locator" xlink:label="us-gaap_BusinessAcquisitionProFormaEarningsPerShareBasic" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_BusinessAcquisitionProFormaEarningsPerShareBasic_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Basic</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BusinessAcquisitionProFormaEarningsPerShareBasic" xlink:to="us-gaap_BusinessAcquisitionProFormaEarningsPerShareBasic_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_BusinessAcquisitionProFormaEarningsPerShareBasic_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Business Acquisition Pro Forma Earnings Per Share Basic</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessAcquisitionProFormaEarningsPerShareDiluted" xlink:type="locator" xlink:label="us-gaap_BusinessAcquisitionProFormaEarningsPerShareDiluted" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_BusinessAcquisitionProFormaEarningsPerShareDiluted_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Diluted</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BusinessAcquisitionProFormaEarningsPerShareDiluted" xlink:to="us-gaap_BusinessAcquisitionProFormaEarningsPerShareDiluted_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_BusinessAcquisitionProFormaEarningsPerShareDiluted_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Business Acquisition Pro Forma Earnings Per Share Diluted</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ChangeInContractWithCustomerLiabilityAbstract" xlink:type="locator" xlink:label="us-gaap_ChangeInContractWithCustomerLiabilityAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ChangeInContractWithCustomerLiabilityAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Change In Contract With Customer Liability [Abstract]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ChangeInContractWithCustomerLiabilityAbstract" xlink:to="us-gaap_ChangeInContractWithCustomerLiabilityAbstract_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_ChangeInContractWithCustomerLiabilityLineItems" xlink:type="locator" xlink:label="mksi_ChangeInContractWithCustomerLiabilityLineItems" />
    <link:label xml:lang="en-US" xlink:label="mksi_ChangeInContractWithCustomerLiabilityLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Change in Contract with Customer, Liability [Line Items]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_ChangeInContractWithCustomerLiabilityLineItems" xlink:to="mksi_ChangeInContractWithCustomerLiabilityLineItems_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_ChangeInContractWithCustomerLiabilityTable" xlink:type="locator" xlink:label="mksi_ChangeInContractWithCustomerLiabilityTable" />
    <link:label xml:lang="en-US" xlink:label="mksi_ChangeInContractWithCustomerLiabilityTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Change in Contract with Customer, Liability [Table]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_ChangeInContractWithCustomerLiabilityTable" xlink:to="mksi_ChangeInContractWithCustomerLiabilityTable_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_ChangeInContractWithCustomerLiabilityTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Change In Contract With Customer Liability [Table]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_ChangeInContractWithCustomerLiabilityTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Change In Contract With Customer Liability [Table]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_ChangeInContractWithCustomerLiabilityLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Change in Contract with Customer, Liability [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_ChangeInContractWithCustomerLiabilityLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Change In Contract With Customer Liability [Line Items]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ContractWithCustomerAssetNet" xlink:type="locator" xlink:label="us-gaap_ContractWithCustomerAssetNet" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ContractWithCustomerAssetNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Contract assets</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ContractWithCustomerAssetNet" xlink:to="us-gaap_ContractWithCustomerAssetNet_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ContractWithCustomerAssetNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Contract With Customer Asset Net</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_ContractWithCustomerLiabilityAdditions" xlink:type="locator" xlink:label="mksi_ContractWithCustomerLiabilityAdditions" />
    <link:label xml:lang="en-US" xlink:label="mksi_ContractWithCustomerLiabilityAdditions_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Contract with customer liability additions.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_ContractWithCustomerLiabilityAdditions" xlink:to="mksi_ContractWithCustomerLiabilityAdditions_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_ContractWithCustomerAmountOfDeferredRevenueAndCustomerAdvancesRecognized" xlink:type="locator" xlink:label="mksi_ContractWithCustomerAmountOfDeferredRevenueAndCustomerAdvancesRecognized" />
    <link:label xml:lang="en-US" xlink:label="mksi_ContractWithCustomerAmountOfDeferredRevenueAndCustomerAdvancesRecognized_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Contract with customer amount of deferred revenue and customer advances recognized</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_ContractWithCustomerAmountOfDeferredRevenueAndCustomerAdvancesRecognized" xlink:to="mksi_ContractWithCustomerAmountOfDeferredRevenueAndCustomerAdvancesRecognized_lbl" />
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ContractWithCustomerLiability" xlink:type="locator" xlink:label="us-gaap_ContractWithCustomerLiability" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ContractWithCustomerLiability_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Beginning balance, January 1</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ContractWithCustomerLiability" xlink:to="us-gaap_ContractWithCustomerLiability_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ContractWithCustomerLiability_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Contract With Customer Liability</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_ContractWithCustomerLiabilityAdditions_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Additions to deferred revenue and customer advances</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_ContractWithCustomerLiabilityAdditions_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Contract With Customer Liability Additions</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_ContractWithCustomerAmountOfDeferredRevenueAndCustomerAdvancesRecognized_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Amount of deferred revenue and customer advances recognized in income</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_ContractWithCustomerAmountOfDeferredRevenueAndCustomerAdvancesRecognized_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Contract With Customer Amount Of Deferred Revenue And Customer Advances Recognized</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_ContractWithCustomerLiability_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Ending balance, December 31</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BalanceSheetLocationAxis" xlink:type="locator" xlink:label="us-gaap_BalanceSheetLocationAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_BalanceSheetLocationAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Balance Sheet Location</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BalanceSheetLocationAxis" xlink:to="us-gaap_BalanceSheetLocationAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_BalanceSheetLocationAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Balance Sheet Location [Axis]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:type="locator" xlink:label="us-gaap_BalanceSheetLocationDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_BalanceSheetLocationDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Balance Sheet Location</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BalanceSheetLocationDomain" xlink:to="us-gaap_BalanceSheetLocationDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_BalanceSheetLocationDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Balance Sheet Location [Domain]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_DeferredRevenueMember" xlink:type="locator" xlink:label="mksi_DeferredRevenueMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_DeferredRevenueMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Deferred Revenue [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_DeferredRevenueMember" xlink:to="mksi_DeferredRevenueMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_DeferredRevenueMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Deferred Revenue [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_DeferredRevenueMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Revenue [Member]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_CustomerAdvancesMember" xlink:type="locator" xlink:label="mksi_CustomerAdvancesMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_CustomerAdvancesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Customer Advances [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_CustomerAdvancesMember" xlink:to="mksi_CustomerAdvancesMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_CustomerAdvancesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Customer Advances [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_CustomerAdvancesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Customer Advances [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ContractWithCustomerLiabilityNoncurrent" xlink:type="locator" xlink:label="us-gaap_ContractWithCustomerLiabilityNoncurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ContractWithCustomerLiabilityNoncurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Long-term deferred revenue</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ContractWithCustomerLiabilityNoncurrent" xlink:to="us-gaap_ContractWithCustomerLiabilityNoncurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ContractWithCustomerLiabilityNoncurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Contract With Customer Liability Noncurrent</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisaggregationOfRevenueTable" xlink:type="locator" xlink:label="us-gaap_DisaggregationOfRevenueTable" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DisaggregationOfRevenueTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Disaggregation Of Revenue [Table]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DisaggregationOfRevenueTable" xlink:to="us-gaap_DisaggregationOfRevenueTable_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DisaggregationOfRevenueTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Disaggregation Of Revenue [Table]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_VacuumAndAnalysisSegmentMember" xlink:type="locator" xlink:label="mksi_VacuumAndAnalysisSegmentMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_VacuumAndAnalysisSegmentMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Vacuum and analysis segment.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_VacuumAndAnalysisSegmentMember" xlink:to="mksi_VacuumAndAnalysisSegmentMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_VacuumAndAnalysisSegmentMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Vacuum &amp; Analysis [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_VacuumAndAnalysisSegmentMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Vacuum And Analysis Segment [Member]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_LightAndMotionSegmentMember" xlink:type="locator" xlink:label="mksi_LightAndMotionSegmentMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_LightAndMotionSegmentMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Light and motion segment.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_LightAndMotionSegmentMember" xlink:to="mksi_LightAndMotionSegmentMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_LightAndMotionSegmentMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Light &amp; Motion [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_LightAndMotionSegmentMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Light And Motion Segment [Member]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_EquipmentAndSolutionsMember" xlink:type="locator" xlink:label="mksi_EquipmentAndSolutionsMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_EquipmentAndSolutionsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Equipment and solutions.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_EquipmentAndSolutionsMember" xlink:to="mksi_EquipmentAndSolutionsMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_EquipmentAndSolutionsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Equipment &amp; Solutions [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_EquipmentAndSolutionsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Equipment And Solutions [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisaggregationOfRevenueLineItems" xlink:type="locator" xlink:label="us-gaap_DisaggregationOfRevenueLineItems" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DisaggregationOfRevenueLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Disaggregation of Revenue [Line Items]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DisaggregationOfRevenueLineItems" xlink:to="us-gaap_DisaggregationOfRevenueLineItems_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DisaggregationOfRevenueLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Disaggregation Of Revenue [Line Items]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InvestmentsAbstract" xlink:type="locator" xlink:label="us-gaap_InvestmentsAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_InvestmentsAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Investments [Abstract]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InvestmentsAbstract" xlink:to="us-gaap_InvestmentsAbstract_lbl" />
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfAvailableForSaleSecuritiesTable" />
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    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfAvailableForSaleSecuritiesTable" xlink:to="us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_lbl" />
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    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InvestmentTypeAxis" xlink:type="locator" xlink:label="us-gaap_InvestmentTypeAxis" />
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    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InvestmentTypeAxis" xlink:to="us-gaap_InvestmentTypeAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_InvestmentTypeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Investment Type [Axis]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:type="locator" xlink:label="us-gaap_InvestmentTypeCategorizationMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_InvestmentTypeCategorizationMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Investments</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InvestmentTypeCategorizationMember" xlink:to="us-gaap_InvestmentTypeCategorizationMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_InvestmentTypeCategorizationMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Investment Type Categorization [Member]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_TimeDepositsAndCertificatesOfDepositMember" xlink:type="locator" xlink:label="mksi_TimeDepositsAndCertificatesOfDepositMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_TimeDepositsAndCertificatesOfDepositMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Time Deposits and Certificates of Deposit [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_TimeDepositsAndCertificatesOfDepositMember" xlink:to="mksi_TimeDepositsAndCertificatesOfDepositMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_TimeDepositsAndCertificatesOfDepositMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Time Deposits and Certificates of Deposit [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_TimeDepositsAndCertificatesOfDepositMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Time Deposits And Certificates Of Deposit [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BankersAcceptanceMember" xlink:type="locator" xlink:label="us-gaap_BankersAcceptanceMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_BankersAcceptanceMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Bankers&apos; Acceptance Drafts [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BankersAcceptanceMember" xlink:to="us-gaap_BankersAcceptanceMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_BankersAcceptanceMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Bankers Acceptance [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommercialPaperMember" xlink:type="locator" xlink:label="us-gaap_CommercialPaperMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CommercialPaperMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Commercial Paper [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommercialPaperMember" xlink:to="us-gaap_CommercialPaperMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CommercialPaperMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Commercial Paper [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_USTreasurySecuritiesMember" xlink:type="locator" xlink:label="us-gaap_USTreasurySecuritiesMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_USTreasurySecuritiesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">U.S. Treasury Obligations [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_USTreasurySecuritiesMember" xlink:to="us-gaap_USTreasurySecuritiesMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_USTreasurySecuritiesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">U S Treasury Securities [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_USGovernmentAgenciesDebtSecuritiesMember" xlink:type="locator" xlink:label="us-gaap_USGovernmentAgenciesDebtSecuritiesMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_USGovernmentAgenciesDebtSecuritiesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">U.S. Agency Obligations [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_USGovernmentAgenciesDebtSecuritiesMember" xlink:to="us-gaap_USGovernmentAgenciesDebtSecuritiesMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_USGovernmentAgenciesDebtSecuritiesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">U S Government Agencies Debt Securities [Member]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_GroupInsuranceContractsMember" xlink:type="locator" xlink:label="mksi_GroupInsuranceContractsMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_GroupInsuranceContractsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Group insurance contracts.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_GroupInsuranceContractsMember" xlink:to="mksi_GroupInsuranceContractsMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_GroupInsuranceContractsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Group Insurance Contracts [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_GroupInsuranceContractsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Group Insurance Contracts [Member]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_Investment1Axis" xlink:type="locator" xlink:label="mksi_Investment1Axis" />
    <link:label xml:lang="en-US" xlink:label="mksi_Investment1Axis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Investment1</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_Investment1Axis" xlink:to="mksi_Investment1Axis_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_Investment1Axis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Investment1 [Axis]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_Investment1Domain" xlink:type="locator" xlink:label="mksi_Investment1Domain" />
    <link:label xml:lang="en-US" xlink:label="mksi_Investment1Domain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Investment1.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_Investment1Domain" xlink:to="mksi_Investment1Domain_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_Investment1Domain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Investment1</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_Investment1Domain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Investment1 [Domain]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_LongTermInvestmentsMember" xlink:type="locator" xlink:label="mksi_LongTermInvestmentsMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_LongTermInvestmentsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Long Term Investments [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_LongTermInvestmentsMember" xlink:to="mksi_LongTermInvestmentsMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_LongTermInvestmentsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Long Term Investments [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_LongTermInvestmentsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Long Term Investments [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems" xlink:type="locator" xlink:label="us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule of Available-for-sale Securities [Line Items]</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Available For Sale Securities [Line Items]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtSecuritiesAvailableForSaleAndHeldToMaturityAmortizedCostAfterAllowanceForCreditLoss" xlink:type="locator" xlink:label="us-gaap_DebtSecuritiesAvailableForSaleAndHeldToMaturityAmortizedCostAfterAllowanceForCreditLoss" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtSecuritiesAvailableForSaleAndHeldToMaturityAmortizedCostAfterAllowanceForCreditLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Investments, Cost</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtSecuritiesAvailableForSaleAndHeldToMaturityAmortizedCostAfterAllowanceForCreditLoss" xlink:to="us-gaap_DebtSecuritiesAvailableForSaleAndHeldToMaturityAmortizedCostAfterAllowanceForCreditLoss_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtSecuritiesAvailableForSaleAndHeldToMaturityAmortizedCostAfterAllowanceForCreditLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Debt Securities Available For Sale And Held To Maturity Amortized Cost After Allowance For Credit Loss</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtSecuritiesAvailableForSaleAndHeldToMaturityCumulativeUnrecognizedGain" xlink:type="locator" xlink:label="us-gaap_DebtSecuritiesAvailableForSaleAndHeldToMaturityCumulativeUnrecognizedGain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtSecuritiesAvailableForSaleAndHeldToMaturityCumulativeUnrecognizedGain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Investments, Gross Unrealized Gains</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtSecuritiesAvailableForSaleAndHeldToMaturityCumulativeUnrecognizedGain" xlink:to="us-gaap_DebtSecuritiesAvailableForSaleAndHeldToMaturityCumulativeUnrecognizedGain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtSecuritiesAvailableForSaleAndHeldToMaturityCumulativeUnrecognizedGain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Debt Securities Available For Sale And Held To Maturity Cumulative Unrecognized Gain</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtSecuritiesAvailableForSaleAndHeldToMaturityCumulativeUnrecognizedLoss" xlink:type="locator" xlink:label="us-gaap_DebtSecuritiesAvailableForSaleAndHeldToMaturityCumulativeUnrecognizedLoss" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtSecuritiesAvailableForSaleAndHeldToMaturityCumulativeUnrecognizedLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Investments, Gross Unrealized (Losses)</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtSecuritiesAvailableForSaleAndHeldToMaturityCumulativeUnrecognizedLoss" xlink:to="us-gaap_DebtSecuritiesAvailableForSaleAndHeldToMaturityCumulativeUnrecognizedLoss_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtSecuritiesAvailableForSaleAndHeldToMaturityCumulativeUnrecognizedLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Debt Securities Available For Sale And Held To Maturity Cumulative Unrecognized Loss</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtSecuritiesAvailableForSaleAndHeldToMaturityFairValue" xlink:type="locator" xlink:label="us-gaap_DebtSecuritiesAvailableForSaleAndHeldToMaturityFairValue" />
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    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtSecuritiesAvailableForSaleAndHeldToMaturityFairValue" xlink:to="us-gaap_DebtSecuritiesAvailableForSaleAndHeldToMaturityFairValue_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtSecuritiesAvailableForSaleAndHeldToMaturityFairValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Debt Securities Available For Sale And Held To Maturity Fair Value</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_CurrentInterestRateFairValueHedgeAssetAtFairValue" xlink:type="locator" xlink:label="mksi_CurrentInterestRateFairValueHedgeAssetAtFairValue" />
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    <link:loc xlink:href="mksi-20211231.xsd#mksi_NonCurrentAssetsFairValueDisclosure" xlink:type="locator" xlink:label="mksi_NonCurrentAssetsFairValueDisclosure" />
    <link:label xml:lang="en-US" xlink:label="mksi_NonCurrentAssetsFairValueDisclosure_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Non current assets fair value disclosure.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_NonCurrentAssetsFairValueDisclosure" xlink:to="mksi_NonCurrentAssetsFairValueDisclosure_lbl" />
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:type="locator" xlink:label="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" />
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    <link:label xml:lang="en-US" xlink:label="us-gaap_FairValueByMeasurementFrequencyAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Measurement Frequency</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueByMeasurementFrequencyAxis" xlink:to="us-gaap_FairValueByMeasurementFrequencyAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FairValueByMeasurementFrequencyAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Fair Value By Measurement Frequency [Axis]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:type="locator" xlink:label="us-gaap_FairValueMeasurementFrequencyDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FairValueMeasurementFrequencyDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Measurement Frequency</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueMeasurementFrequencyDomain" xlink:to="us-gaap_FairValueMeasurementFrequencyDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FairValueMeasurementFrequencyDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Fair Value Measurement Frequency [Domain]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember" xlink:type="locator" xlink:label="us-gaap_FairValueMeasurementsRecurringMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FairValueMeasurementsRecurringMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Fair Value Measurements, Recurring [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueMeasurementsRecurringMember" xlink:to="us-gaap_FairValueMeasurementsRecurringMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FairValueMeasurementsRecurringMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Fair Value Measurements Recurring [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:type="locator" xlink:label="us-gaap_FairValueByFairValueHierarchyLevelAxis" />
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    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AssetsFairValueDisclosure" xlink:type="locator" xlink:label="us-gaap_AssetsFairValueDisclosure" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AssetsFairValueDisclosure_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total assets</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AssetsFairValueDisclosure" xlink:to="us-gaap_AssetsFairValueDisclosure_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AssetsFairValueDisclosure_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Assets Fair Value Disclosure</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ForeignCurrencyCashFlowHedgeLiabilityAtFairValue" xlink:type="locator" xlink:label="us-gaap_ForeignCurrencyCashFlowHedgeLiabilityAtFairValue" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ForeignCurrencyCashFlowHedgeLiabilityAtFairValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/positiveVerboseLabel">Derivatives &#8211; forward exchange contracts</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ForeignCurrencyCashFlowHedgeLiabilityAtFairValue" xlink:to="us-gaap_ForeignCurrencyCashFlowHedgeLiabilityAtFairValue_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ForeignCurrencyCashFlowHedgeLiabilityAtFairValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Foreign Currency Cash Flow Hedge Liability At Fair Value</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_NonCurrentInterestRateFairValueHedgeLiabilitiesAtFairValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/positiveVerboseLabel">Derivatives &#8211; interest rate hedge &#8211; non-current</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_NonCurrentInterestRateFairValueHedgeLiabilitiesAtFairValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Non Current Interest Rate Fair Value Hedge Liabilities At Fair Value</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeLiabilities" xlink:type="locator" xlink:label="us-gaap_DerivativeLiabilities" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DerivativeLiabilities_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total liabilities</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DerivativeLiabilities" xlink:to="us-gaap_DerivativeLiabilities_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DerivativeLiabilities_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Derivative Liabilities</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_OtherCurrentAssetsFairValueDisclosure_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other current assets</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_OtherCurrentAssetsFairValueDisclosure_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Other Current Assets Fair Value Disclosure</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_CurrentAssetsFairValueDisclosure_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total current assets</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_CurrentAssetsFairValueDisclosure_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Current Assets Fair Value Disclosure</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecuritiesNoncurrent" xlink:type="locator" xlink:label="us-gaap_AvailableForSaleSecuritiesDebtSecuritiesNoncurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AvailableForSaleSecuritiesDebtSecuritiesNoncurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Long-term investments</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AvailableForSaleSecuritiesDebtSecuritiesNoncurrent" xlink:to="us-gaap_AvailableForSaleSecuritiesDebtSecuritiesNoncurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AvailableForSaleSecuritiesDebtSecuritiesNoncurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Available For Sale Securities Debt Securities Noncurrent</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_OtherNonCurrentAssetsFairValueDisclosure_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other assets</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_OtherNonCurrentAssetsFairValueDisclosure_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Other Non Current Assets Fair Value Disclosure</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_NonCurrentAssetsFairValueDisclosure_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total long-term assets</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_NonCurrentAssetsFairValueDisclosure_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Non Current Assets Fair Value Disclosure</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable" xlink:type="locator" xlink:label="us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Derivative Instruments And Hedging Activities Disclosures [Table]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable" xlink:to="us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Derivative Instruments And Hedging Activities Disclosures [Table]</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_ForeignExchangeForwardMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Foreign Exchange Contracts [Member]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_AtotechLimitedMember" xlink:type="locator" xlink:label="mksi_AtotechLimitedMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_AtotechLimitedMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Atotech Limited.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_AtotechLimitedMember" xlink:to="mksi_AtotechLimitedMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_AtotechLimitedMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Atotech [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_AtotechLimitedMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Atotech Limited [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Debt Instrument</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentAxis" xlink:to="us-gaap_DebtInstrumentAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument [Axis]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentNameDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentNameDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Debt Instrument, Name</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="us-gaap_DebtInstrumentNameDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentNameDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument Name [Domain]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_TermLoanMember" xlink:type="locator" xlink:label="mksi_TermLoanMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_TermLoanMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Term loan.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_TermLoanMember" xlink:to="mksi_TermLoanMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_TermLoanMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Term Loan [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_TermLoanMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Term Loan [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherOperatingIncomeExpenseMember" xlink:type="locator" xlink:label="us-gaap_OtherOperatingIncomeExpenseMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OtherOperatingIncomeExpenseMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other Expense, Net [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherOperatingIncomeExpenseMember" xlink:to="us-gaap_OtherOperatingIncomeExpenseMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OtherOperatingIncomeExpenseMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Other Operating Income Expense [Member]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_PhotonControlMember" xlink:type="locator" xlink:label="mksi_PhotonControlMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_PhotonControlMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Photon Control.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_PhotonControlMember" xlink:to="mksi_PhotonControlMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_PhotonControlMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Photon Control [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_PhotonControlMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Photon Control [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems" xlink:type="locator" xlink:label="us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Derivative Instruments and Hedging Activities Disclosures [Line Items]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems" xlink:to="us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Derivative Instruments And Hedging Activities Disclosures [Line Items]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_MaximumRemainingMaturityOfForeignCurrencyDerivatives1" xlink:type="locator" xlink:label="us-gaap_MaximumRemainingMaturityOfForeignCurrencyDerivatives1" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_MaximumRemainingMaturityOfForeignCurrencyDerivatives1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Maximum period for hedging a portion of forecasted foreign currency denominated intercompany sales of inventory</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_MaximumRemainingMaturityOfForeignCurrencyDerivatives1" xlink:to="us-gaap_MaximumRemainingMaturityOfForeignCurrencyDerivatives1_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_MaximumRemainingMaturityOfForeignCurrencyDerivatives1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Maximum Remaining Maturity Of Foreign Currency Derivatives1</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeAssetNotionalAmount" xlink:type="locator" xlink:label="us-gaap_DerivativeAssetNotionalAmount" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DerivativeAssetNotionalAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Gross notional values of outstanding forward foreign exchange contracts</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DerivativeAssetNotionalAmount" xlink:to="us-gaap_DerivativeAssetNotionalAmount_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DerivativeAssetNotionalAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Derivative Asset Notional Amount</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeTable" xlink:type="locator" xlink:label="us-gaap_DerivativeTable" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DerivativeTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Derivative [Table]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DerivativeTable" xlink:to="us-gaap_DerivativeTable_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DerivativeTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Derivative [Table]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis" xlink:type="locator" xlink:label="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Hedging Relationship</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis" xlink:to="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Derivative Instruments Gain Loss By Hedging Relationship [Axis]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_HedgingRelationshipDomain" xlink:type="locator" xlink:label="us-gaap_HedgingRelationshipDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_HedgingRelationshipDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Hedging Relationship</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_HedgingRelationshipDomain" xlink:to="us-gaap_HedgingRelationshipDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_HedgingRelationshipDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Hedging Relationship [Domain]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_USDollarJapaneseYenMember" xlink:type="locator" xlink:label="mksi_USDollarJapaneseYenMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_USDollarJapaneseYenMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">U S Dollar Japanese Yen [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_USDollarJapaneseYenMember" xlink:to="mksi_USDollarJapaneseYenMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_USDollarJapaneseYenMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">U.S. Dollar/Japanese Yen [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_USDollarJapaneseYenMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">U S Dollar Japanese Yen [Member]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_USDollarKoreanWonMember" xlink:type="locator" xlink:label="mksi_USDollarKoreanWonMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_USDollarKoreanWonMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">U S Dollar Korean Won [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_USDollarKoreanWonMember" xlink:to="mksi_USDollarKoreanWonMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_USDollarKoreanWonMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">U.S. Dollar/South Korean Won [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_USDollarKoreanWonMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">U S Dollar Korean Won [Member]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_USDollarEuroMember" xlink:type="locator" xlink:label="mksi_USDollarEuroMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_USDollarEuroMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">U S Dollar Euro [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_USDollarEuroMember" xlink:to="mksi_USDollarEuroMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_USDollarEuroMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">U.S. Dollar/Euro [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_USDollarEuroMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">U S Dollar Euro [Member]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_UsDollarUkPoundMember" xlink:type="locator" xlink:label="mksi_UsDollarUkPoundMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_UsDollarUkPoundMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">US Dollar UK Pound [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_UsDollarUkPoundMember" xlink:to="mksi_UsDollarUkPoundMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_UsDollarUkPoundMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">U.S. Dollar/U.K. Pound Sterling [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_UsDollarUkPoundMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Us Dollar Uk Pound [Member]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_USDollarTaiwaneseDollarsMember" xlink:type="locator" xlink:label="mksi_USDollarTaiwaneseDollarsMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_USDollarTaiwaneseDollarsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">U S Dollar Taiwanese Dollars [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_USDollarTaiwaneseDollarsMember" xlink:to="mksi_USDollarTaiwaneseDollarsMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_USDollarTaiwaneseDollarsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">U.S. Dollar/Taiwan Dollar [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_USDollarTaiwaneseDollarsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">U S Dollar Taiwanese Dollars [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeLineItems" xlink:type="locator" xlink:label="us-gaap_DerivativeLineItems" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DerivativeLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Derivative [Line Items]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DerivativeLineItems" xlink:to="us-gaap_DerivativeLineItems_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DerivativeLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Derivative [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_DerivativeAssetNotionalAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Currency Hedged (Buy/Sell), Gross Notional Value, Net</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ForeignCurrencyCashFlowHedgeDerivativeAtFairValueNet" xlink:type="locator" xlink:label="us-gaap_ForeignCurrencyCashFlowHedgeDerivativeAtFairValueNet" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ForeignCurrencyCashFlowHedgeDerivativeAtFairValueNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Currency Hedged (Buy/Sell), Fair Value, (Liability)/Asset, Net</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ForeignCurrencyCashFlowHedgeDerivativeAtFairValueNet" xlink:to="us-gaap_ForeignCurrencyCashFlowHedgeDerivativeAtFairValueNet_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ForeignCurrencyCashFlowHedgeDerivativeAtFairValueNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Foreign Currency Cash Flow Hedge Derivative At Fair Value Net</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_DerivativeTradeDates" xlink:type="locator" xlink:label="mksi_DerivativeTradeDates" />
    <link:label xml:lang="en-US" xlink:label="mksi_DerivativeTradeDates_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Derivative trade dates.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_DerivativeTradeDates" xlink:to="mksi_DerivativeTradeDates_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_DerivativeEffectiveDates" xlink:type="locator" xlink:label="mksi_DerivativeEffectiveDates" />
    <link:label xml:lang="en-US" xlink:label="mksi_DerivativeEffectiveDates_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Derivative effective dates.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_DerivativeEffectiveDates" xlink:to="mksi_DerivativeEffectiveDates_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_IncrementalTermLoanFacilityMember" xlink:type="locator" xlink:label="mksi_IncrementalTermLoanFacilityMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_IncrementalTermLoanFacilityMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Incremental Term Loan Facility [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_IncrementalTermLoanFacilityMember" xlink:to="mksi_IncrementalTermLoanFacilityMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_IncrementalTermLoanFacilityMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Incremental Term Loan Facility [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_IncrementalTermLoanFacilityMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Incremental Term Loan Facility [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CreditFacilityAxis" xlink:type="locator" xlink:label="us-gaap_CreditFacilityAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CreditFacilityAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Credit Facility</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CreditFacilityAxis" xlink:to="us-gaap_CreditFacilityAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CreditFacilityAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Credit Facility [Axis]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:type="locator" xlink:label="us-gaap_CreditFacilityDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CreditFacilityDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Credit Facility</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CreditFacilityDomain" xlink:to="us-gaap_CreditFacilityDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CreditFacilityDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Credit Facility [Domain]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_SwapAgreementOneMember" xlink:type="locator" xlink:label="mksi_SwapAgreementOneMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_SwapAgreementOneMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Swap Agreement One.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_SwapAgreementOneMember" xlink:to="mksi_SwapAgreementOneMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_SwapAgreementOneMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Swap Agreement One [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_SwapAgreementOneMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Swap Agreement One [Member]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_SwapAgreementTwoMember" xlink:type="locator" xlink:label="mksi_SwapAgreementTwoMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_SwapAgreementTwoMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Swap agreement two.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_SwapAgreementTwoMember" xlink:to="mksi_SwapAgreementTwoMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_SwapAgreementTwoMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Swap Agreement Two [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_SwapAgreementTwoMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Swap Agreement Two [Member]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_SwapAgreementThreeMember" xlink:type="locator" xlink:label="mksi_SwapAgreementThreeMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_SwapAgreementThreeMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Swap agreement three.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_SwapAgreementThreeMember" xlink:to="mksi_SwapAgreementThreeMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_SwapAgreementThreeMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Swap Agreement Three [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_SwapAgreementThreeMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Swap Agreement Three [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_DerivativeTradeDates_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Trade Date</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_DerivativeTradeDates_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Derivative Trade Dates</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_DerivativeEffectiveDates_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Effective Date</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_DerivativeEffectiveDates_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Derivative Effective Dates</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeMaturityDates" xlink:type="locator" xlink:label="us-gaap_DerivativeMaturityDates" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DerivativeMaturityDates_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Maturity</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DerivativeMaturityDates" xlink:to="us-gaap_DerivativeMaturityDates_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DerivativeMaturityDates_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Derivative Maturity Dates</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeFixedInterestRate" xlink:type="locator" xlink:label="us-gaap_DerivativeFixedInterestRate" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DerivativeFixedInterestRate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Fixed Rate</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DerivativeFixedInterestRate" xlink:to="us-gaap_DerivativeFixedInterestRate_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DerivativeFixedInterestRate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Derivative Fixed Interest Rate</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeNotionalAmount" xlink:type="locator" xlink:label="us-gaap_DerivativeNotionalAmount" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DerivativeNotionalAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Notional Amount at Effective Date</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DerivativeNotionalAmount" xlink:to="us-gaap_DerivativeNotionalAmount_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DerivativeNotionalAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Derivative Notional Amount</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeFairValueOfDerivativeNet" xlink:type="locator" xlink:label="us-gaap_DerivativeFairValueOfDerivativeNet" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DerivativeFairValueOfDerivativeNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Fair Value Asset (Liability)</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DerivativeFairValueOfDerivativeNet" xlink:to="us-gaap_DerivativeFairValueOfDerivativeNet_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DerivativeFairValueOfDerivativeNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Derivative Fair Value Of Derivative Net</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_DerivativeNotionalAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Notional amount in EUR/USD</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_OptionAgreementMember" xlink:type="locator" xlink:label="mksi_OptionAgreementMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_OptionAgreementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Option agreements.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_OptionAgreementMember" xlink:to="mksi_OptionAgreementMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_OptionAgreementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Option Agreement [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_OptionAgreementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Option Agreement [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ForeignCurrencyTransactionGainLossUnrealized" xlink:type="locator" xlink:label="us-gaap_ForeignCurrencyTransactionGainLossUnrealized" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ForeignCurrencyTransactionGainLossUnrealized_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Unrealized gain net of premium</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ForeignCurrencyTransactionGainLossUnrealized" xlink:to="us-gaap_ForeignCurrencyTransactionGainLossUnrealized_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ForeignCurrencyTransactionGainLossUnrealized_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Foreign Currency Transaction Gain Loss Unrealized</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GainLossOnForeignCurrencyFairValueHedgeDerivatives" xlink:type="locator" xlink:label="us-gaap_GainLossOnForeignCurrencyFairValueHedgeDerivatives" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_GainLossOnForeignCurrencyFairValueHedgeDerivatives_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Fair value realized loss</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_GainLossOnForeignCurrencyFairValueHedgeDerivatives" xlink:to="us-gaap_GainLossOnForeignCurrencyFairValueHedgeDerivatives_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_GainLossOnForeignCurrencyFairValueHedgeDerivatives_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Gain Loss On Foreign Currency Fair Value Hedge Derivatives</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable" xlink:type="locator" xlink:label="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Derivative Instruments Gain Loss By Hedging Relationship By Income Statement Location By Derivative Instrument Risk [Table]</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Derivative Instruments Gain Loss By Hedging Relationship By Income Statement Location By Derivative Instrument Risk [Table]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CashFlowHedgingMember" xlink:type="locator" xlink:label="us-gaap_CashFlowHedgingMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CashFlowHedgingMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Cash Flow Hedging [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CashFlowHedgingMember" xlink:to="us-gaap_CashFlowHedgingMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CashFlowHedgingMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Cash Flow Hedging [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossLineItems" xlink:type="locator" xlink:label="us-gaap_DerivativeInstrumentsGainLossLineItems" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DerivativeInstrumentsGainLossLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Derivative Instruments, Gain (Loss) [Line Items]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DerivativeInstrumentsGainLossLineItems" xlink:to="us-gaap_DerivativeInstrumentsGainLossLineItems_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DerivativeInstrumentsGainLossLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Derivative Instruments Gain Loss [Line Items]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeGainLossOnDerivativeNet" xlink:type="locator" xlink:label="us-gaap_DerivativeGainLossOnDerivativeNet" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DerivativeGainLossOnDerivativeNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Net gain (loss) recognized in OCI, net of tax</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DerivativeGainLossOnDerivativeNet" xlink:to="us-gaap_DerivativeGainLossOnDerivativeNet_lbl" />
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    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet" xlink:type="locator" xlink:label="us-gaap_DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet" />
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    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAbstract" xlink:type="locator" xlink:label="us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAbstract" />
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    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GainLossOnForeignCurrencyDerivativeInstrumentsNotDesignatedAsHedgingInstruments" xlink:type="locator" xlink:label="us-gaap_GainLossOnForeignCurrencyDerivativeInstrumentsNotDesignatedAsHedgingInstruments" />
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    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InventoryRawMaterialsNetOfReserves" xlink:type="locator" xlink:label="us-gaap_InventoryRawMaterialsNetOfReserves" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_InventoryRawMaterialsNetOfReserves_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Raw material</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_InventoryRawMaterialsNetOfReserves_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Inventory Raw Materials Net Of Reserves</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InventoryWorkInProcessNetOfReserves" xlink:type="locator" xlink:label="us-gaap_InventoryWorkInProcessNetOfReserves" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_InventoryWorkInProcessNetOfReserves_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Work-in-process</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_InventoryWorkInProcessNetOfReserves_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Inventory Work In Process Net Of Reserves</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InventoryFinishedGoodsNetOfReserves" xlink:type="locator" xlink:label="us-gaap_InventoryFinishedGoodsNetOfReserves" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_InventoryFinishedGoodsNetOfReserves_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Finished goods</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InventoryFinishedGoodsNetOfReserves" xlink:to="us-gaap_InventoryFinishedGoodsNetOfReserves_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_InventoryFinishedGoodsNetOfReserves_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Inventory Finished Goods Net Of Reserves</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_InventoryNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Inventories</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_InventoryWriteDown_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Inventory related excess and obsolete charges</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule Of Property Plant And Equipment [Table]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:to="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Property Plant And Equipment [Table]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LandMember" xlink:type="locator" xlink:label="us-gaap_LandMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LandMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Land [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LandMember" xlink:to="us-gaap_LandMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LandMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Land [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BuildingAndBuildingImprovementsMember" xlink:type="locator" xlink:label="us-gaap_BuildingAndBuildingImprovementsMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_BuildingAndBuildingImprovementsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Building and Building Improvements [Member]</link:label>
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    <link:loc xlink:href="mksi-20211231.xsd#mksi_FurnitureAndFixturesOfficeEquipmentAndSoftwareMember" xlink:type="locator" xlink:label="mksi_FurnitureAndFixturesOfficeEquipmentAndSoftwareMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_FurnitureAndFixturesOfficeEquipmentAndSoftwareMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Furniture and fixtures office equipment and software [Member].</link:label>
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    <link:label xml:lang="en-US" xlink:label="mksi_FurnitureAndFixturesOfficeEquipmentAndSoftwareMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Furniture And Fixtures Office Equipment And Software [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LeaseholdImprovementsMember" xlink:type="locator" xlink:label="us-gaap_LeaseholdImprovementsMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LeaseholdImprovementsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Leasehold Improvements [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LeaseholdImprovementsMember" xlink:to="us-gaap_LeaseholdImprovementsMember_lbl" />
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    <link:label xml:lang="en-US" xlink:label="us-gaap_PropertyPlantAndEquipmentLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Property Plant And Equipment [Line Items]</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_PropertyPlantAndEquipmentGross_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Property, plant and equipment</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_PropertyPlantAndEquipmentGross_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Property Plant And Equipment Gross</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" xlink:type="locator" xlink:label="us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Less: accumulated depreciation</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_Depreciation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Depreciation of property, plant and equipment</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_Depreciation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Depreciation</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseCost_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating lease</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseCost_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease Cost</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_ShortTermLeaseCost_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Short-term lease</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_ShortTermLeaseCost_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Short Term Lease Cost</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LeaseCost" xlink:type="locator" xlink:label="us-gaap_LeaseCost" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LeaseCost_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total lease cost</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_LeaseCost_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lease Cost</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_TenantImprovementsAllowanceReceipts" xlink:type="locator" xlink:label="mksi_TenantImprovementsAllowanceReceipts" />
    <link:label xml:lang="en-US" xlink:label="mksi_TenantImprovementsAllowanceReceipts_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Tenant improvements allowance receipts.</link:label>
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    <link:loc xlink:href="mksi-20211231.xsd#mksi_LeasesLineItems" xlink:type="locator" xlink:label="mksi_LeasesLineItems" />
    <link:label xml:lang="en-US" xlink:label="mksi_LeasesLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Leases.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_LeasesLineItems" xlink:to="mksi_LeasesLineItems_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_LeasesTable" xlink:type="locator" xlink:label="mksi_LeasesTable" />
    <link:label xml:lang="en-US" xlink:label="mksi_LeasesTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Leases.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_LeasesTable" xlink:to="mksi_LeasesTable_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_LeasesTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Leases [Table]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_LeasesTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Leases [Table]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_StatementGeographicalAxis" xlink:type="locator" xlink:label="srt_StatementGeographicalAxis" />
    <link:label xml:lang="en-US" xlink:label="srt_StatementGeographicalAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Geographical</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_StatementGeographicalAxis" xlink:to="srt_StatementGeographicalAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="srt_StatementGeographicalAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Statement Geographical [Axis]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_SegmentGeographicalDomain" xlink:type="locator" xlink:label="srt_SegmentGeographicalDomain" />
    <link:label xml:lang="en-US" xlink:label="srt_SegmentGeographicalDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Geographical</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_SegmentGeographicalDomain" xlink:to="srt_SegmentGeographicalDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="srt_SegmentGeographicalDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Segment Geographical [Domain]</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/stpr/2021/stpr-2021.xsd#stpr_CO" xlink:type="locator" xlink:label="stpr_CO" />
    <link:label xml:lang="en-US" xlink:label="stpr_CO_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Boulder, Colorado [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="stpr_CO" xlink:to="stpr_CO_lbl" />
    <link:label xml:lang="en-US" xlink:label="stpr_CO_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">COLORADO</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/stpr/2021/stpr-2021.xsd#stpr_OR" xlink:type="locator" xlink:label="stpr_OR" />
    <link:label xml:lang="en-US" xlink:label="stpr_OR_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Portland, Oregon [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="stpr_OR" xlink:to="stpr_OR_lbl" />
    <link:label xml:lang="en-US" xlink:label="stpr_OR_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">OREGON</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_LeasesLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Leases [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_LeasesLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Leases [Line Items]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent" xlink:type="locator" xlink:label="us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Weighted average discount rate</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent" xlink:to="us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease Weighted Average Discount Rate Percent</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1" xlink:type="locator" xlink:label="us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Weighted average remaining lease term</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1" xlink:to="us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease Weighted Average Remaining Lease Term1</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeasePayments" xlink:type="locator" xlink:label="us-gaap_OperatingLeasePayments" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeasePayments_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating cash flows used for operating leases</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingLeasePayments" xlink:to="us-gaap_OperatingLeasePayments_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeasePayments_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease Payments</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_TenantImprovementsAllowanceReceipts_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Tenant improvement allowance receipts</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_TenantImprovementsAllowanceReceipts_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Tenant Improvements Allowance Receipts</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_NumberOfPropertiesSoldAsPartOfSaleAndLeasebackTransactions" xlink:type="locator" xlink:label="mksi_NumberOfPropertiesSoldAsPartOfSaleAndLeasebackTransactions" />
    <link:label xml:lang="en-US" xlink:label="mksi_NumberOfPropertiesSoldAsPartOfSaleAndLeasebackTransactions_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Number of properties sold as part of sale and leaseback transactions.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_NumberOfPropertiesSoldAsPartOfSaleAndLeasebackTransactions" xlink:to="mksi_NumberOfPropertiesSoldAsPartOfSaleAndLeasebackTransactions_lbl" />
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SaleAndLeasebackTransactionGainLossNet" xlink:type="locator" xlink:label="us-gaap_SaleAndLeasebackTransactionGainLossNet" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SaleAndLeasebackTransactionGainLossNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Gain loss on sale lease back</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SaleAndLeasebackTransactionGainLossNet" xlink:to="us-gaap_SaleAndLeasebackTransactionGainLossNet_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SaleAndLeasebackTransactionGainLossNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Sale And Leaseback Transaction Gain Loss Net</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SaleLeasebackTransactionNetProceedsInvestingActivities" xlink:type="locator" xlink:label="us-gaap_SaleLeasebackTransactionNetProceedsInvestingActivities" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SaleLeasebackTransactionNetProceedsInvestingActivities_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Proceeds received on sale lease back transactions</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SaleLeasebackTransactionNetProceedsInvestingActivities" xlink:to="us-gaap_SaleLeasebackTransactionNetProceedsInvestingActivities_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SaleLeasebackTransactionNetProceedsInvestingActivities_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Sale Leaseback Transaction Net Proceeds Investing Activities</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_NumberOfPropertiesSoldAsPartOfSaleAndLeasebackTransactions_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Number of properties sold as part of sale and leaseback transactions</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_NumberOfPropertiesSoldAsPartOfSaleAndLeasebackTransactions_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Number Of Properties Sold As Part Of Sale And Leaseback Transactions</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths" xlink:type="locator" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2022</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lessee Operating Lease Liability Payments Due Next Twelve Months</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo" xlink:type="locator" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2023</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lessee Operating Lease Liability Payments Due Year Two</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree" xlink:type="locator" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2024</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lessee Operating Lease Liability Payments Due Year Three</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour" xlink:type="locator" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2025</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lessee Operating Lease Liability Payments Due Year Four</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive" xlink:type="locator" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2026</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lessee Operating Lease Liability Payments Due Year Five</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive" xlink:type="locator" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Thereafter</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lessee Operating Lease Liability Payments Due After Year Five</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" xlink:type="locator" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total lease payments</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lessee Operating Lease Liability Payments Due</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount" xlink:type="locator" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Less: imputed interest</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lessee Operating Lease Liability Undiscounted Excess Amount</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeaseLiability" xlink:type="locator" xlink:label="us-gaap_OperatingLeaseLiability" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseLiability_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Total lease liabilities</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingLeaseLiability" xlink:to="us-gaap_OperatingLeaseLiability_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseLiability_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease Liability</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">2021 lease payment</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PaymentsForProceedsFromTenantAllowance" xlink:type="locator" xlink:label="us-gaap_PaymentsForProceedsFromTenantAllowance" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PaymentsForProceedsFromTenantAllowance_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Tenant improvement allowance</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PaymentsForProceedsFromTenantAllowance" xlink:to="us-gaap_PaymentsForProceedsFromTenantAllowance_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PaymentsForProceedsFromTenantAllowance_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Payments For Proceeds From Tenant Allowance</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_GoodwillAcquiredDuringPeriodGross" xlink:type="locator" xlink:label="mksi_GoodwillAcquiredDuringPeriodGross" />
    <link:label xml:lang="en-US" xlink:label="mksi_GoodwillAcquiredDuringPeriodGross_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Goodwill acquired during period gross.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_GoodwillAcquiredDuringPeriodGross" xlink:to="mksi_GoodwillAcquiredDuringPeriodGross_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_GoodwillImpairmentLossGross" xlink:type="locator" xlink:label="mksi_GoodwillImpairmentLossGross" />
    <link:label xml:lang="en-US" xlink:label="mksi_GoodwillImpairmentLossGross_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Goodwill impairment loss gross.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_GoodwillImpairmentLossGross" xlink:to="mksi_GoodwillImpairmentLossGross_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_GoodwillTranslationAdjustmentsGross" xlink:type="locator" xlink:label="mksi_GoodwillTranslationAdjustmentsGross" />
    <link:label xml:lang="en-US" xlink:label="mksi_GoodwillTranslationAdjustmentsGross_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Goodwill translation adjustments gross.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_GoodwillTranslationAdjustmentsGross" xlink:to="mksi_GoodwillTranslationAdjustmentsGross_lbl" />
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GoodwillGross" xlink:type="locator" xlink:label="us-gaap_GoodwillGross" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_GoodwillGross_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Beginning balance, Goodwill Gross Carrying Amount</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_GoodwillGross" xlink:to="us-gaap_GoodwillGross_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_GoodwillGross_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Goodwill Gross</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_GoodwillAcquiredDuringPeriodGross_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Acquired goodwill, Gross Carrying Amount</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_GoodwillAcquiredDuringPeriodGross_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Goodwill Acquired During Period Gross</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_GoodwillImpairmentLossGross_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Impairment of goodwill, Gross Carrying Amount</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_GoodwillImpairmentLossGross_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Goodwill Impairment Loss Gross</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_GoodwillTranslationAdjustmentsGross_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Foreign currency translation, Gross Carrying Amount</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_GoodwillTranslationAdjustmentsGross_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Goodwill Translation Adjustments Gross</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_GoodwillGross_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Ending balance, Goodwill Gross Carrying Amount</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GoodwillImpairedAccumulatedImpairmentLoss" xlink:type="locator" xlink:label="us-gaap_GoodwillImpairedAccumulatedImpairmentLoss" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_GoodwillImpairedAccumulatedImpairmentLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedPeriodStartLabel">Beginning balance, Accumulated Impairment Loss</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_GoodwillImpairedAccumulatedImpairmentLoss" xlink:to="us-gaap_GoodwillImpairedAccumulatedImpairmentLoss_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_GoodwillImpairedAccumulatedImpairmentLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Goodwill Impaired Accumulated Impairment Loss</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GoodwillImpairmentLoss" xlink:type="locator" xlink:label="us-gaap_GoodwillImpairmentLoss" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_GoodwillImpairmentLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Impairment of goodwill, Accumulated Impairment Loss</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_GoodwillImpairmentLoss" xlink:to="us-gaap_GoodwillImpairmentLoss_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_GoodwillImpairmentLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Goodwill Impairment Loss</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_GoodwillImpairedAccumulatedImpairmentLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedPeriodEndLabel">Ending balance, Accumulated Impairment Loss</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_Goodwill_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Beginning balance, Goodwill Net</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GoodwillAcquiredDuringPeriod" xlink:type="locator" xlink:label="us-gaap_GoodwillAcquiredDuringPeriod" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_GoodwillAcquiredDuringPeriod_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Acquired goodwill, Net</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_GoodwillAcquiredDuringPeriod" xlink:to="us-gaap_GoodwillAcquiredDuringPeriod_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_GoodwillAcquiredDuringPeriod_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Goodwill Acquired During Period</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_GoodwillImpairmentLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel">Impairment of goodwill, Net</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GoodwillForeignCurrencyTranslationGainLoss" xlink:type="locator" xlink:label="us-gaap_GoodwillForeignCurrencyTranslationGainLoss" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_GoodwillForeignCurrencyTranslationGainLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Foreign currency translation, Net</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_GoodwillForeignCurrencyTranslationGainLoss" xlink:to="us-gaap_GoodwillForeignCurrencyTranslationGainLoss_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_GoodwillForeignCurrencyTranslationGainLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Goodwill Foreign Currency Translation Gain Loss</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_Goodwill_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Ending balance, Goodwill Net</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule Of Finite Lived Intangible Assets [Table]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" xlink:to="us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Finite Lived Intangible Assets [Table]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PatentedTechnologyMember" xlink:type="locator" xlink:label="us-gaap_PatentedTechnologyMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PatentedTechnologyMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Completed Technology [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PatentedTechnologyMember" xlink:to="us-gaap_PatentedTechnologyMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PatentedTechnologyMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Patented Technology [Member]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_PatentsTrademarksTradeNamesAndOtherMember" xlink:type="locator" xlink:label="mksi_PatentsTrademarksTradeNamesAndOtherMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_PatentsTrademarksTradeNamesAndOtherMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Patents trademarks trade names and other.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_PatentsTrademarksTradeNamesAndOtherMember" xlink:to="mksi_PatentsTrademarksTradeNamesAndOtherMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_PatentsTrademarksTradeNamesAndOtherMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Patents, Trademarks, Trade Names and Other [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_PatentsTrademarksTradeNamesAndOtherMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Patents Trademarks Trade Names And Other [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:type="locator" xlink:label="us-gaap_FiniteLivedIntangibleAssetsLineItems" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Finite-Lived Intangible Assets [Line Items]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:to="us-gaap_FiniteLivedIntangibleAssetsLineItems_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finite Lived Intangible Assets [Line Items]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsGross" xlink:type="locator" xlink:label="us-gaap_FiniteLivedIntangibleAssetsGross" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsGross_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Intangible assets, Gross</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsGross" xlink:to="us-gaap_FiniteLivedIntangibleAssetsGross_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsGross_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finite Lived Intangible Assets Gross</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill" xlink:type="locator" xlink:label="us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Accumulated Impairment Charges</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill" xlink:to="us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Impairment Of Intangible Assets Indefinitelived Excluding Goodwill</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" xlink:type="locator" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Accumulated Amortization</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" xlink:to="us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finite Lived Intangible Assets Accumulated Amortization</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsForeignCurrencyTranslationGainLoss" xlink:type="locator" xlink:label="us-gaap_FiniteLivedIntangibleAssetsForeignCurrencyTranslationGainLoss" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsForeignCurrencyTranslationGainLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Foreign Currency Translation</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsForeignCurrencyTranslationGainLoss" xlink:to="us-gaap_FiniteLivedIntangibleAssetsForeignCurrencyTranslationGainLoss_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsForeignCurrencyTranslationGainLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finite Lived Intangible Assets Foreign Currency Translation Gain Loss</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_TrademarksTradenamesAndBacklogMember" xlink:type="locator" xlink:label="mksi_TrademarksTradenamesAndBacklogMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_TrademarksTradenamesAndBacklogMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Trademarks Tradenames and Backlog</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_TrademarksTradenamesAndBacklogMember" xlink:to="mksi_TrademarksTradenamesAndBacklogMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_TrademarksTradenamesAndBacklogMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Trademarks Tradenames And Backlog</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_TrademarksTradenamesAndBacklogMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Trademarks Tradenames And Backlog [Member]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_GoodwillAndIntangibleAssetsLineItems" xlink:type="locator" xlink:label="mksi_GoodwillAndIntangibleAssetsLineItems" />
    <link:label xml:lang="en-US" xlink:label="mksi_GoodwillAndIntangibleAssetsLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Goodwill and intangible assets.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_GoodwillAndIntangibleAssetsLineItems" xlink:to="mksi_GoodwillAndIntangibleAssetsLineItems_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_GoodwillAndIntangibleAssetsTable" xlink:type="locator" xlink:label="mksi_GoodwillAndIntangibleAssetsTable" />
    <link:label xml:lang="en-US" xlink:label="mksi_GoodwillAndIntangibleAssetsTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Goodwill and intangible assets.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_GoodwillAndIntangibleAssetsTable" xlink:to="mksi_GoodwillAndIntangibleAssetsTable_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_GoodwillAndIntangibleAssetsTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Goodwill And Intangible Assets [Table]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_GoodwillAndIntangibleAssetsTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Goodwill And Intangible Assets [Table]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis" xlink:type="locator" xlink:label="us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Indefinite-lived Intangible Assets</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis" xlink:to="us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Indefinite Lived Intangible Assets By Major Class [Axis]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:type="locator" xlink:label="us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Indefinite-lived Intangible Assets, Major Class Name</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Indefinite Lived Intangible Assets Major Class Name [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_TrademarksAndTradeNamesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Trademarks and Trade Names [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_GoodwillAndIntangibleAssetsLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Goodwill And Intangible Assets [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_GoodwillAndIntangibleAssetsLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Goodwill And Intangible Assets [Line Items]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill" xlink:type="locator" xlink:label="us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Un-amortized Intangible assets, net</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Indefinite Lived Intangible Assets Excluding Goodwill</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths" xlink:type="locator" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2022</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths" xlink:to="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finite Lived Intangible Assets Amortization Expense Next Twelve Months</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo" xlink:type="locator" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2023</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo" xlink:to="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finite Lived Intangible Assets Amortization Expense Year Two</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree" xlink:type="locator" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2024</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree" xlink:to="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finite Lived Intangible Assets Amortization Expense Year Three</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour" xlink:type="locator" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2025</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour" xlink:to="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finite Lived Intangible Assets Amortization Expense Year Four</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive" xlink:type="locator" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2026</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive" xlink:to="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finite Lived Intangible Assets Amortization Expense Year Five</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive" xlink:type="locator" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Thereafter</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive" xlink:to="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finite Lived Intangible Assets Amortization Expense After Year Five</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GuaranteesAbstract" xlink:type="locator" xlink:label="us-gaap_GuaranteesAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_GuaranteesAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Guarantees [Abstract]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_GuaranteesAbstract" xlink:to="us-gaap_GuaranteesAbstract_lbl" />
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProductWarrantyLiabilityTable" xlink:type="locator" xlink:label="us-gaap_ProductWarrantyLiabilityTable" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ProductWarrantyLiabilityTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Product Warranty Liability [Table]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProductWarrantyLiabilityTable" xlink:to="us-gaap_ProductWarrantyLiabilityTable_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ProductWarrantyLiabilityTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Product Warranty Liability [Table]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProductWarrantyLiabilityLineItems" xlink:type="locator" xlink:label="us-gaap_ProductWarrantyLiabilityLineItems" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ProductWarrantyLiabilityLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Product Warranty Liability [Line Items]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProductWarrantyLiabilityLineItems" xlink:to="us-gaap_ProductWarrantyLiabilityLineItems_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ProductWarrantyLiabilityLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Product Warranty Liability [Line Items]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProductWarrantyAccrual" xlink:type="locator" xlink:label="us-gaap_ProductWarrantyAccrual" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ProductWarrantyAccrual_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Beginning balance</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProductWarrantyAccrual" xlink:to="us-gaap_ProductWarrantyAccrual_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ProductWarrantyAccrual_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Product Warranty Accrual</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProductWarrantyAccrualWarrantiesIssued" xlink:type="locator" xlink:label="us-gaap_ProductWarrantyAccrualWarrantiesIssued" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ProductWarrantyAccrualWarrantiesIssued_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Provision for product warranties</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProductWarrantyAccrualWarrantiesIssued" xlink:to="us-gaap_ProductWarrantyAccrualWarrantiesIssued_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ProductWarrantyAccrualWarrantiesIssued_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Product Warranty Accrual Warranties Issued</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ExtendedProductWarrantyAccrualAdditionsFromBusinessAcquisition" xlink:type="locator" xlink:label="us-gaap_ExtendedProductWarrantyAccrualAdditionsFromBusinessAcquisition" />
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    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProductWarrantyAccrualPeriodIncreaseDecrease" xlink:type="locator" xlink:label="us-gaap_ProductWarrantyAccrualPeriodIncreaseDecrease" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ProductWarrantyAccrualPeriodIncreaseDecrease_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Direct and other charges to warranty liability</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_ProductWarrantyAccrualPeriodIncreaseDecrease_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Product Warranty Accrual Period Increase Decrease</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_ProductWarrantyAccrual_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Ending balance</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProductWarrantyAccrualClassifiedCurrent" xlink:type="locator" xlink:label="us-gaap_ProductWarrantyAccrualClassifiedCurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ProductWarrantyAccrualClassifiedCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Short-term product warranties</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_ProductWarrantyAccrualClassifiedCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Product Warranty Accrual Classified Current</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProductWarrantyAccrualNoncurrent" xlink:type="locator" xlink:label="us-gaap_ProductWarrantyAccrualNoncurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ProductWarrantyAccrualNoncurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Long-term product warranties</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProductWarrantyAccrualNoncurrent" xlink:to="us-gaap_ProductWarrantyAccrualNoncurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ProductWarrantyAccrualNoncurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Product Warranty Accrual Noncurrent</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_ShortTermBorrowingsAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Short Term Borrowings [Abstract]</link:label>
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    <link:loc xlink:href="https://xbrl.sec.gov/country/2021/country-2021.xsd#country_JP" xlink:type="locator" xlink:label="country_JP" />
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    <link:loc xlink:href="mksi-20211231.xsd#mksi_LinesOfCreditAndFinancingFacilityMember" xlink:type="locator" xlink:label="mksi_LinesOfCreditAndFinancingFacilityMember" />
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    <link:loc xlink:href="mksi-20211231.xsd#mksi_TermLoanFacilityMember" xlink:type="locator" xlink:label="mksi_TermLoanFacilityMember" />
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    <link:label xml:lang="en-US" xlink:label="us-gaap_ShortTermDebtLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Short Term Debt [Line Items]</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_ShortTermDebtLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Short Term Debt [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShortTermBorrowings_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Short term debt</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_LongTermDebtAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Long Term Debt [Abstract]</link:label>
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    <link:loc xlink:href="mksi-20211231.xsd#mksi_TermLoanFacilityNetMember" xlink:type="locator" xlink:label="mksi_TermLoanFacilityNetMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_TermLoanFacilityNetMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Term loan facility, net.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_TermLoanFacilityNetMember" xlink:to="mksi_TermLoanFacilityNetMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_TermLoanFacilityNetMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Term Loan Facility, Net [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_TermLoanFacilityNetMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Term Loan Facility Net [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentLineItems" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Debt Instrument [Line Items]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentLineItems_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_LongTermDebt_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Long term debt</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredFinanceCostsNoncurrentNet" xlink:type="locator" xlink:label="us-gaap_DeferredFinanceCostsNoncurrentNet" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredFinanceCostsNoncurrentNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Deferred financing fees, original issuance discount and re-pricing fee</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredFinanceCostsNoncurrentNet" xlink:to="us-gaap_DeferredFinanceCostsNoncurrentNet_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredFinanceCostsNoncurrentNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Finance Costs Noncurrent Net</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InterestExpenseLongTermDebt" xlink:type="locator" xlink:label="us-gaap_InterestExpenseLongTermDebt" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_InterestExpenseLongTermDebt_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Interest expense</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InterestExpenseLongTermDebt" xlink:to="us-gaap_InterestExpenseLongTermDebt_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_InterestExpenseLongTermDebt_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Interest Expense Long Term Debt</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_NewportCorporationMember" xlink:type="locator" xlink:label="mksi_NewportCorporationMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_NewportCorporationMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Newport Corporation.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_NewportCorporationMember" xlink:to="mksi_NewportCorporationMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_NewportCorporationMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Newport Corporation [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_NewportCorporationMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Newport Corporation [Member]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_TermLoanCreditAgreementMember" xlink:type="locator" xlink:label="mksi_TermLoanCreditAgreementMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_TermLoanCreditAgreementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Term loan credit agreement.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_TermLoanCreditAgreementMember" xlink:to="mksi_TermLoanCreditAgreementMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_TermLoanCreditAgreementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Term Loan Facility [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_TermLoanCreditAgreementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Term Loan Credit Agreement [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SecuredDebtMember" xlink:type="locator" xlink:label="us-gaap_SecuredDebtMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SecuredDebtMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Secured Debt [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SecuredDebtMember" xlink:to="us-gaap_SecuredDebtMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SecuredDebtMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Secured Debt [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_VariableRateAxis" xlink:type="locator" xlink:label="us-gaap_VariableRateAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_VariableRateAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Variable Rate</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_VariableRateAxis" xlink:to="us-gaap_VariableRateAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_VariableRateAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Variable Rate [Axis]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_VariableRateDomain" xlink:type="locator" xlink:label="us-gaap_VariableRateDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_VariableRateDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Variable Rate</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_VariableRateDomain" xlink:to="us-gaap_VariableRateDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_VariableRateDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Variable Rate [Domain]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BaseRateMember" xlink:type="locator" xlink:label="us-gaap_BaseRateMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_BaseRateMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Base Rate [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BaseRateMember" xlink:to="us-gaap_BaseRateMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_BaseRateMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Base Rate [Member]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_FederalFundsRateMember" xlink:type="locator" xlink:label="mksi_FederalFundsRateMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_FederalFundsRateMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Federal funds rate.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_FederalFundsRateMember" xlink:to="mksi_FederalFundsRateMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_FederalFundsRateMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Federal Funds Rate [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_FederalFundsRateMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Federal Funds Rate [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LondonInterbankOfferedRateLIBORMember" xlink:type="locator" xlink:label="us-gaap_LondonInterbankOfferedRateLIBORMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LondonInterbankOfferedRateLIBORMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">LIBOR [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LondonInterbankOfferedRateLIBORMember" xlink:to="us-gaap_LondonInterbankOfferedRateLIBORMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LondonInterbankOfferedRateLIBORMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">London Interbank Offered Rate L I B O R [Member]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_AdjustedOneMonthLiborMember" xlink:type="locator" xlink:label="mksi_AdjustedOneMonthLiborMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_AdjustedOneMonthLiborMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Adjusted one month LIBOR.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_AdjustedOneMonthLiborMember" xlink:to="mksi_AdjustedOneMonthLiborMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_AdjustedOneMonthLiborMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Adjusted One Month LIBOR [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_AdjustedOneMonthLiborMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Adjusted One Month Libor [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InterestRateFloorMember" xlink:type="locator" xlink:label="us-gaap_InterestRateFloorMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_InterestRateFloorMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Floor Rate [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InterestRateFloorMember" xlink:to="us-gaap_InterestRateFloorMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_InterestRateFloorMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Interest Rate Floor [Member]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_MayTermLoanAmendmentMember" xlink:type="locator" xlink:label="mksi_MayTermLoanAmendmentMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_MayTermLoanAmendmentMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">May term loan amendment.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_MayTermLoanAmendmentMember" xlink:to="mksi_MayTermLoanAmendmentMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_MayTermLoanAmendmentMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">May Term Loan Amendment [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_MayTermLoanAmendmentMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">May Term Loan Amendment [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentFaceAmount" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentFaceAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Secured term loan, face amount</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentFaceAmount" xlink:to="us-gaap_DebtInstrumentFaceAmount_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentFaceAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument Face Amount</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongTermDebtMaturityDate" xlink:type="locator" xlink:label="us-gaap_LongTermDebtMaturityDate" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LongTermDebtMaturityDate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Term loan maturity date</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LongTermDebtMaturityDate" xlink:to="us-gaap_LongTermDebtMaturityDate_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LongTermDebtMaturityDate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Long Term Debt Maturity Date</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentInterestRateTerms" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentInterestRateTerms" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentInterestRateTerms_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Debt instrument, interest rate terms</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentInterestRateTerms" xlink:to="us-gaap_DebtInstrumentInterestRateTerms_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentInterestRateTerms_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument Interest Rate Terms</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Debt instrument, interest rate</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" xlink:to="us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument Basis Spread On Variable Rate1</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_LineOfCreditFacilityMinimumAdditionalBorrowingCapacity" xlink:type="locator" xlink:label="mksi_LineOfCreditFacilityMinimumAdditionalBorrowingCapacity" />
    <link:label xml:lang="en-US" xlink:label="mksi_LineOfCreditFacilityMinimumAdditionalBorrowingCapacity_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Line of credit facility minimum additional borrowing capacity.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_LineOfCreditFacilityMinimumAdditionalBorrowingCapacity" xlink:to="mksi_LineOfCreditFacilityMinimumAdditionalBorrowingCapacity_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_MinimumPercentageOfEarningsBeforeInterestTaxesDepreciationAndAmortization" xlink:type="locator" xlink:label="mksi_MinimumPercentageOfEarningsBeforeInterestTaxesDepreciationAndAmortization" />
    <link:label xml:lang="en-US" xlink:label="mksi_MinimumPercentageOfEarningsBeforeInterestTaxesDepreciationAndAmortization_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Minimum percentage of earnings before interest taxes depreciation and amortization.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_MinimumPercentageOfEarningsBeforeInterestTaxesDepreciationAndAmortization" xlink:to="mksi_MinimumPercentageOfEarningsBeforeInterestTaxesDepreciationAndAmortization_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_LineOfCreditFacilityMinimumAdditionalBorrowingCapacity_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Line of credit facility minimum additional borrowing capacity</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_LineOfCreditFacilityMinimumAdditionalBorrowingCapacity_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Line Of Credit Facility Minimum Additional Borrowing Capacity</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_MinimumPercentageOfEarningsBeforeInterestTaxesDepreciationAndAmortization_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Minimum percentage of consolidated EBITDA</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_MinimumPercentageOfEarningsBeforeInterestTaxesDepreciationAndAmortization_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Minimum Percentage Of Earnings Before Interest Taxes Depreciation And Amortization</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RatioOfIndebtednessToNetCapital1" xlink:type="locator" xlink:label="us-gaap_RatioOfIndebtednessToNetCapital1" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RatioOfIndebtednessToNetCapital1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Leverage ratio</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RatioOfIndebtednessToNetCapital1" xlink:to="us-gaap_RatioOfIndebtednessToNetCapital1_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RatioOfIndebtednessToNetCapital1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Ratio Of Indebtedness To Net Capital1</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_DebtInstrumentPeriodicPaymentPercentage" xlink:type="locator" xlink:label="mksi_DebtInstrumentPeriodicPaymentPercentage" />
    <link:label xml:lang="en-US" xlink:label="mksi_DebtInstrumentPeriodicPaymentPercentage_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Debt instrument, periodic payment percentage.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_DebtInstrumentPeriodicPaymentPercentage" xlink:to="mksi_DebtInstrumentPeriodicPaymentPercentage_lbl" />
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentFrequencyOfPeriodicPayment" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentFrequencyOfPeriodicPayment" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentFrequencyOfPeriodicPayment_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Debt instrument, frequency of periodic payment</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentFrequencyOfPeriodicPayment" xlink:to="us-gaap_DebtInstrumentFrequencyOfPeriodicPayment_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentFrequencyOfPeriodicPayment_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument Frequency Of Periodic Payment</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_DebtInstrumentPeriodicPaymentPercentage_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Debt instrument, periodic payment percentage</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_DebtInstrumentPeriodicPaymentPercentage_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument Periodic Payment Percentage</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_PercentageOfBorrowingBasedOnEligibleAccountsReceivable" xlink:type="locator" xlink:label="mksi_PercentageOfBorrowingBasedOnEligibleAccountsReceivable" />
    <link:label xml:lang="en-US" xlink:label="mksi_PercentageOfBorrowingBasedOnEligibleAccountsReceivable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Percentage of borrowing based on eligible accounts receivable.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_PercentageOfBorrowingBasedOnEligibleAccountsReceivable" xlink:to="mksi_PercentageOfBorrowingBasedOnEligibleAccountsReceivable_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_PercentageOfBorrowingBasedOnLowerOfNetBookValueOfEligibleInventory" xlink:type="locator" xlink:label="mksi_PercentageOfBorrowingBasedOnLowerOfNetBookValueOfEligibleInventory" />
    <link:label xml:lang="en-US" xlink:label="mksi_PercentageOfBorrowingBasedOnLowerOfNetBookValueOfEligibleInventory_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Percentage of borrowing based on lower of net book value of eligible inventory.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_PercentageOfBorrowingBasedOnLowerOfNetBookValueOfEligibleInventory" xlink:to="mksi_PercentageOfBorrowingBasedOnLowerOfNetBookValueOfEligibleInventory_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_PercentageOfBorrowingBase" xlink:type="locator" xlink:label="mksi_PercentageOfBorrowingBase" />
    <link:label xml:lang="en-US" xlink:label="mksi_PercentageOfBorrowingBase_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Percentage of borrowing base.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_PercentageOfBorrowingBase" xlink:to="mksi_PercentageOfBorrowingBase_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_PercentageOfBorrowingBasedOnLowerOfCostOrMarketValueOfCertainEligibleInventory" xlink:type="locator" xlink:label="mksi_PercentageOfBorrowingBasedOnLowerOfCostOrMarketValueOfCertainEligibleInventory" />
    <link:label xml:lang="en-US" xlink:label="mksi_PercentageOfBorrowingBasedOnLowerOfCostOrMarketValueOfCertainEligibleInventory_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Percentage of borrowing based on lower of cost or market value of certain eligible inventory.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_PercentageOfBorrowingBasedOnLowerOfCostOrMarketValueOfCertainEligibleInventory" xlink:to="mksi_PercentageOfBorrowingBasedOnLowerOfCostOrMarketValueOfCertainEligibleInventory_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_PercentageOfBorrowingBasedOnNetOrderlyLiquidationValueOfCertainEligibleInventory" xlink:type="locator" xlink:label="mksi_PercentageOfBorrowingBasedOnNetOrderlyLiquidationValueOfCertainEligibleInventory" />
    <link:label xml:lang="en-US" xlink:label="mksi_PercentageOfBorrowingBasedOnNetOrderlyLiquidationValueOfCertainEligibleInventory_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Percentage of borrowing based on net orderly liquidation value of certain eligible inventory.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_PercentageOfBorrowingBasedOnNetOrderlyLiquidationValueOfCertainEligibleInventory" xlink:to="mksi_PercentageOfBorrowingBasedOnNetOrderlyLiquidationValueOfCertainEligibleInventory_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_AssetBasedCreditAgreementMember" xlink:type="locator" xlink:label="mksi_AssetBasedCreditAgreementMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_AssetBasedCreditAgreementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Asset based credit agreement.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_AssetBasedCreditAgreementMember" xlink:to="mksi_AssetBasedCreditAgreementMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_AssetBasedCreditAgreementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Asset Based Credit Agreement [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_AssetBasedCreditAgreementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Asset Based Credit Agreement [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevolvingCreditFacilityMember" xlink:type="locator" xlink:label="us-gaap_RevolvingCreditFacilityMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RevolvingCreditFacilityMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Revolving Lines of Credit [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RevolvingCreditFacilityMember" xlink:to="us-gaap_RevolvingCreditFacilityMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RevolvingCreditFacilityMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Revolving Credit Facility [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LetterOfCreditMember" xlink:type="locator" xlink:label="us-gaap_LetterOfCreditMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LetterOfCreditMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Letter of Credit [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LetterOfCreditMember" xlink:to="us-gaap_LetterOfCreditMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LetterOfCreditMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Letter Of Credit [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_PercentageOfBorrowingBasedOnEligibleAccountsReceivable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Percentage of borrowing based on eligible accounts</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_PercentageOfBorrowingBasedOnEligibleAccountsReceivable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Percentage Of Borrowing Based On Eligible Accounts Receivable</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_PercentageOfBorrowingBasedOnLowerOfNetBookValueOfEligibleInventory_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Percentage of borrowing based on lower of net book value of eligible inventory</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_PercentageOfBorrowingBasedOnLowerOfNetBookValueOfEligibleInventory_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Percentage Of Borrowing Based On Lower Of Net Book Value Of Eligible Inventory</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_PercentageOfBorrowingBase_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Percentage of borrowing base</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_PercentageOfBorrowingBase_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Percentage Of Borrowing Base</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_PercentageOfBorrowingBasedOnLowerOfCostOrMarketValueOfCertainEligibleInventory_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Percentage of borrowing based on lower of cost or market value of certain eligible inventory</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_PercentageOfBorrowingBasedOnLowerOfCostOrMarketValueOfCertainEligibleInventory_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Percentage Of Borrowing Based On Lower Of Cost Or Market Value Of Certain Eligible Inventory</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_PercentageOfBorrowingBasedOnNetOrderlyLiquidationValueOfCertainEligibleInventory_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Percentage of borrowing based on net orderly liquidation value of certain eligible inventory</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_PercentageOfBorrowingBasedOnNetOrderlyLiquidationValueOfCertainEligibleInventory_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Percentage Of Borrowing Based On Net Orderly Liquidation Value Of Certain Eligible Inventory</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:type="locator" xlink:label="us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Borrowing capacity in the form of letters of credit</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:to="us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Line Of Credit Facility Maximum Borrowing Capacity</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage" xlink:type="locator" xlink:label="us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Initial commitment fee percentage</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage" xlink:to="us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Line Of Credit Facility Unused Capacity Commitment Fee Percentage</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_NumberOfConsecutiveBusinessDaysForBorrowingBase" xlink:type="locator" xlink:label="mksi_NumberOfConsecutiveBusinessDaysForBorrowingBase" />
    <link:label xml:lang="en-US" xlink:label="mksi_NumberOfConsecutiveBusinessDaysForBorrowingBase_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Number of consecutive business days for borrowing base.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_NumberOfConsecutiveBusinessDaysForBorrowingBase" xlink:to="mksi_NumberOfConsecutiveBusinessDaysForBorrowingBase_lbl" />
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LineOfCreditFacilityCommitmentFeePercentage" xlink:type="locator" xlink:label="us-gaap_LineOfCreditFacilityCommitmentFeePercentage" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LineOfCreditFacilityCommitmentFeePercentage_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Percentage of commitment amount available</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LineOfCreditFacilityCommitmentFeePercentage" xlink:to="us-gaap_LineOfCreditFacilityCommitmentFeePercentage_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LineOfCreditFacilityCommitmentFeePercentage_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Line Of Credit Facility Commitment Fee Percentage</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity" xlink:type="locator" xlink:label="us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Availability under credit facility</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity" xlink:to="us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Line Of Credit Facility Remaining Borrowing Capacity</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_NumberOfConsecutiveBusinessDaysForBorrowingBase_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Number of consecutive business days for borrowing base</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_NumberOfConsecutiveBusinessDaysForBorrowingBase_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Number Of Consecutive Business Days For Borrowing Base</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentSubjectiveAccelerationClause" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentSubjectiveAccelerationClause" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentSubjectiveAccelerationClause_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Clause to accelerate the scheduled maturities</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentSubjectiveAccelerationClause" xlink:to="us-gaap_DebtInstrumentSubjectiveAccelerationClause_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentSubjectiveAccelerationClause_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument Subjective Acceleration Clause</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_MinimumTermLoanWithEarlierMaturityThanAssetBasedLineFacility" xlink:type="locator" xlink:label="mksi_MinimumTermLoanWithEarlierMaturityThanAssetBasedLineFacility" />
    <link:label xml:lang="en-US" xlink:label="mksi_MinimumTermLoanWithEarlierMaturityThanAssetBasedLineFacility_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Minimum term loan with earlier maturity than asset based line facility.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_MinimumTermLoanWithEarlierMaturityThanAssetBasedLineFacility" xlink:to="mksi_MinimumTermLoanWithEarlierMaturityThanAssetBasedLineFacility_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_MinimumTermLoanWithEarlierMaturityThanAssetBasedLineFacility_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Minimum term loan with earlier maturity than ABL facility subject to spring maturity</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_MinimumTermLoanWithEarlierMaturityThanAssetBasedLineFacility_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Minimum Term Loan With Earlier Maturity Than Asset Based Line Facility</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_PercentageOfLineOfCreditFacilityExcessAvailabilityCommitmentFee" xlink:type="locator" xlink:label="mksi_PercentageOfLineOfCreditFacilityExcessAvailabilityCommitmentFee" />
    <link:label xml:lang="en-US" xlink:label="mksi_PercentageOfLineOfCreditFacilityExcessAvailabilityCommitmentFee_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Percentage of Line of credit facility excess availability commitment fee.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_PercentageOfLineOfCreditFacilityExcessAvailabilityCommitmentFee" xlink:to="mksi_PercentageOfLineOfCreditFacilityExcessAvailabilityCommitmentFee_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_LineOfCreditFacilityExcessAvailabilityAmount" xlink:type="locator" xlink:label="mksi_LineOfCreditFacilityExcessAvailabilityAmount" />
    <link:label xml:lang="en-US" xlink:label="mksi_LineOfCreditFacilityExcessAvailabilityAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Line of credit facility excess availability amount.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_LineOfCreditFacilityExcessAvailabilityAmount" xlink:to="mksi_LineOfCreditFacilityExcessAvailabilityAmount_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_FixedChargeCoverageRatio" xlink:type="locator" xlink:label="mksi_FixedChargeCoverageRatio" />
    <link:label xml:lang="en-US" xlink:label="mksi_FixedChargeCoverageRatio_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Fixed charge coverage ratio.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_FixedChargeCoverageRatio" xlink:to="mksi_FixedChargeCoverageRatio_lbl" />
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentCollateral" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentCollateral" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentCollateral_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Debt instrument, collateral</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentCollateral" xlink:to="us-gaap_DebtInstrumentCollateral_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentCollateral_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument Collateral</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_PercentageOfLineOfCreditFacilityExcessAvailabilityCommitmentFee_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Percentage of line of credit facility excess availability commitment fee</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_PercentageOfLineOfCreditFacilityExcessAvailabilityCommitmentFee_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Percentage Of Line Of Credit Facility Excess Availability Commitment Fee</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_LineOfCreditFacilityExcessAvailabilityAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Line of credit facility excess availability amount</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_LineOfCreditFacilityExcessAvailabilityAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Line Of Credit Facility Excess Availability Amount</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_FixedChargeCoverageRatio_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Fixed charge coverage ratio</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_FixedChargeCoverageRatio_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Fixed Charge Coverage Ratio</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentCovenantDescription" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentCovenantDescription" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentCovenantDescription_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Clause to maintain a Fixed Charge Coverage Ratio</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentCovenantDescription" xlink:to="us-gaap_DebtInstrumentCovenantDescription_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentCovenantDescription_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument Covenant Description</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_LineOfCreditFacilityRenewalPeriod" xlink:type="locator" xlink:label="mksi_LineOfCreditFacilityRenewalPeriod" />
    <link:label xml:lang="en-US" xlink:label="mksi_LineOfCreditFacilityRenewalPeriod_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Line Of Credit Facility Renewal Period.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_LineOfCreditFacilityRenewalPeriod" xlink:to="mksi_LineOfCreditFacilityRenewalPeriod_lbl" />
    <link:loc xlink:href="https://xbrl.sec.gov/exch/2021/exch-2021.xsd#exch_JPBX" xlink:type="locator" xlink:label="exch_JPBX" />
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    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="exch_JPBX" xlink:to="exch_JPBX_lbl" />
    <link:label xml:lang="en-US" xlink:label="exch_JPBX_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">J P B X</link:label>
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    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LineOfCredit" xlink:type="locator" xlink:label="us-gaap_LineOfCredit" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LineOfCredit_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Total borrowings outstanding</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LineOfCredit" xlink:to="us-gaap_LineOfCredit_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LineOfCredit_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Line Of Credit</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_MaturitiesOfLongTermDebtAbstract" xlink:type="locator" xlink:label="us-gaap_MaturitiesOfLongTermDebtAbstract" />
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    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths" xlink:type="locator" xlink:label="us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2022</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Long Term Debt Maturities Repayments Of Principal In Next Twelve Months</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo" xlink:type="locator" xlink:label="us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2023</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Long Term Debt Maturities Repayments Of Principal In Year Two</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree" xlink:type="locator" xlink:label="us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2024</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree" xlink:to="us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Long Term Debt Maturities Repayments Of Principal In Year Three</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour" xlink:type="locator" xlink:label="us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2025</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour" xlink:to="us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Long Term Debt Maturities Repayments Of Principal In Year Four</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive" xlink:type="locator" xlink:label="us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2026</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive" xlink:to="us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Long Term Debt Maturities Repayments Of Principal In Year Five</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_EffectiveIncomeTaxRateReconciliationExecutiveCompensation" xlink:type="locator" xlink:label="mksi_EffectiveIncomeTaxRateReconciliationExecutiveCompensation" />
    <link:label xml:lang="en-US" xlink:label="mksi_EffectiveIncomeTaxRateReconciliationExecutiveCompensation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Effective income tax rate reconciliation executive compensation.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_EffectiveIncomeTaxRateReconciliationExecutiveCompensation" xlink:to="mksi_EffectiveIncomeTaxRateReconciliationExecutiveCompensation_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_EffectiveIncomeTaxRateReconciliationGainOnIntercompanySaleOfAssets" xlink:type="locator" xlink:label="mksi_EffectiveIncomeTaxRateReconciliationGainOnIntercompanySaleOfAssets" />
    <link:label xml:lang="en-US" xlink:label="mksi_EffectiveIncomeTaxRateReconciliationGainOnIntercompanySaleOfAssets_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Effective income tax rate reconciliation gain on intercompany sale of assets.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_EffectiveIncomeTaxRateReconciliationGainOnIntercompanySaleOfAssets" xlink:to="mksi_EffectiveIncomeTaxRateReconciliationGainOnIntercompanySaleOfAssets_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_EffectiveIncomeTaxRateReconciliationUtilizationOfACapitalLoss" xlink:type="locator" xlink:label="mksi_EffectiveIncomeTaxRateReconciliationUtilizationOfACapitalLoss" />
    <link:label xml:lang="en-US" xlink:label="mksi_EffectiveIncomeTaxRateReconciliationUtilizationOfACapitalLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Effective income tax rate reconciliation utilization of a capital loss.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_EffectiveIncomeTaxRateReconciliationUtilizationOfACapitalLoss" xlink:to="mksi_EffectiveIncomeTaxRateReconciliationUtilizationOfACapitalLoss_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_EffectiveIncomeTaxRateReconciliationForeignDerivedIntangibleIncome" xlink:type="locator" xlink:label="mksi_EffectiveIncomeTaxRateReconciliationForeignDerivedIntangibleIncome" />
    <link:label xml:lang="en-US" xlink:label="mksi_EffectiveIncomeTaxRateReconciliationForeignDerivedIntangibleIncome_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Effective income tax rate reconciliation foreign derived intangible income.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_EffectiveIncomeTaxRateReconciliationForeignDerivedIntangibleIncome" xlink:to="mksi_EffectiveIncomeTaxRateReconciliationForeignDerivedIntangibleIncome_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_EffectiveIncomeTaxRateReconciliationRevaluationOfDeferredTax" xlink:type="locator" xlink:label="mksi_EffectiveIncomeTaxRateReconciliationRevaluationOfDeferredTax" />
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    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_EffectiveIncomeTaxRateReconciliationRevaluationOfDeferredTax" xlink:to="mksi_EffectiveIncomeTaxRateReconciliationRevaluationOfDeferredTax_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_EffectiveIncomeTaxRateReconciliationReleaseOfIncomeTaxReserves" xlink:type="locator" xlink:label="mksi_EffectiveIncomeTaxRateReconciliationReleaseOfIncomeTaxReserves" />
    <link:label xml:lang="en-US" xlink:label="mksi_EffectiveIncomeTaxRateReconciliationReleaseOfIncomeTaxReserves_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Effective Income Tax Rate Reconciliation Release of Income Tax Reserves.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_EffectiveIncomeTaxRateReconciliationReleaseOfIncomeTaxReserves" xlink:to="mksi_EffectiveIncomeTaxRateReconciliationReleaseOfIncomeTaxReserves_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_EffectiveIncomeTaxRateReconciliationWithholdingTaxesOnForeignDividendsNetOfForeignTax" xlink:type="locator" xlink:label="mksi_EffectiveIncomeTaxRateReconciliationWithholdingTaxesOnForeignDividendsNetOfForeignTax" />
    <link:label xml:lang="en-US" xlink:label="mksi_EffectiveIncomeTaxRateReconciliationWithholdingTaxesOnForeignDividendsNetOfForeignTax_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Effective income tax rate reconciliation withholding taxes on foreign dividends net of foreign tax.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_EffectiveIncomeTaxRateReconciliationWithholdingTaxesOnForeignDividendsNetOfForeignTax" xlink:to="mksi_EffectiveIncomeTaxRateReconciliationWithholdingTaxesOnForeignDividendsNetOfForeignTax_lbl" />
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate" xlink:type="locator" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">U.S. federal income tax statutory rate</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate" xlink:to="us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationTaxCredits" xlink:type="locator" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationTaxCredits" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationTaxCredits_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Federal tax credits</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationTaxCredits_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Effective Income Tax Rate Reconciliation Tax Credits</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes" xlink:type="locator" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">State income taxes, net of federal benefit</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes" xlink:to="us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Effective Income Tax Rate Reconciliation State And Local Income Taxes</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationForeignIncomeTaxRateDifferential" xlink:type="locator" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationForeignIncomeTaxRateDifferential" />
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    <link:label xml:lang="en-US" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationForeignIncomeTaxRateDifferential_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Effective Income Tax Rate Reconciliation Foreign Income Tax Rate Differential</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_EffectiveIncomeTaxRateReconciliationExecutiveCompensation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Executive compensation</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_EffectiveIncomeTaxRateReconciliationExecutiveCompensation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Effective Income Tax Rate Reconciliation Executive Compensation</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_EffectiveIncomeTaxRateReconciliationGainOnIntercompanySaleOfAssets_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Gain on intercompany sale of assets</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_EffectiveIncomeTaxRateReconciliationGainOnIntercompanySaleOfAssets_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Effective Income Tax Rate Reconciliation Gain On Intercompany Sale Of Assets</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_EffectiveIncomeTaxRateReconciliationUtilizationOfACapitalLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Utilization of a capital loss</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_EffectiveIncomeTaxRateReconciliationUtilizationOfACapitalLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Effective Income Tax Rate Reconciliation Utilization Of A Capital Loss</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_EffectiveIncomeTaxRateReconciliationForeignDerivedIntangibleIncome_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Foreign derived intangible income</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_EffectiveIncomeTaxRateReconciliationForeignDerivedIntangibleIncome_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Effective Income Tax Rate Reconciliation Foreign Derived Intangible Income</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate" xlink:type="locator" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Global intangible low taxed income, net of foreign tax credits</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate" xlink:to="us-gaap_EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Effective Income Tax Rate Reconciliation Change In Enacted Tax Rate</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_EffectiveIncomeTaxRateReconciliationRevaluationOfDeferredTax_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Revaluation of U.S. deferred income taxes</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_EffectiveIncomeTaxRateReconciliationRevaluationOfDeferredTax_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Effective Income Tax Rate Reconciliation Revaluation Of Deferred Tax</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseShareBasedCompensationCost" xlink:type="locator" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseShareBasedCompensationCost" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseShareBasedCompensationCost_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Stock-based compensation</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseShareBasedCompensationCost_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Effective Income Tax Rate Reconciliation Nondeductible Expense Share Based Compensation Cost</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance" xlink:type="locator" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Deferred tax asset valuation allowance</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance" xlink:to="us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Effective Income Tax Rate Reconciliation Change In Deferred Tax Assets Valuation Allowance</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_EffectiveIncomeTaxRateReconciliationReleaseOfIncomeTaxReserves_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Release of income tax reserves (including interest)</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_EffectiveIncomeTaxRateReconciliationReleaseOfIncomeTaxReserves_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Effective Income Tax Rate Reconciliation Release Of Income Tax Reserves</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_EffectiveIncomeTaxRateReconciliationWithholdingTaxesOnForeignDividendsNetOfForeignTax_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Withholding taxes on foreign dividends, net of foreign tax credits</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_EffectiveIncomeTaxRateReconciliationWithholdingTaxesOnForeignDividendsNetOfForeignTax_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Effective Income Tax Rate Reconciliation Withholding Taxes On Foreign Dividends Net Of Foreign Tax</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationOtherAdjustments" xlink:type="locator" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationOtherAdjustments" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationOtherAdjustments_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EffectiveIncomeTaxRateReconciliationOtherAdjustments" xlink:to="us-gaap_EffectiveIncomeTaxRateReconciliationOtherAdjustments_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationOtherAdjustments_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Effective Income Tax Rate Reconciliation Other Adjustments</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EffectiveIncomeTaxRateContinuingOperations" xlink:type="locator" xlink:label="us-gaap_EffectiveIncomeTaxRateContinuingOperations" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EffectiveIncomeTaxRateContinuingOperations_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EffectiveIncomeTaxRateContinuingOperations" xlink:to="us-gaap_EffectiveIncomeTaxRateContinuingOperations_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EffectiveIncomeTaxRateContinuingOperations_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Effective Income Tax Rate Continuing Operations</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_DeferredStateLocalAndForeignIncomeTaxExpenseBenefit" xlink:type="locator" xlink:label="mksi_DeferredStateLocalAndForeignIncomeTaxExpenseBenefit" />
    <link:label xml:lang="en-US" xlink:label="mksi_DeferredStateLocalAndForeignIncomeTaxExpenseBenefit_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">The component of total income tax expense for the period comprised of the increase (decrease) in the entity&apos;s state, local and foreign deferred tax assets and liabilities attributable to continuing operations as determined by applying the provisions of the applicable enacted tax laws.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_DeferredStateLocalAndForeignIncomeTaxExpenseBenefit" xlink:to="mksi_DeferredStateLocalAndForeignIncomeTaxExpenseBenefit_lbl" />
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestmentsAbstract" xlink:type="locator" xlink:label="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestmentsAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestmentsAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Income before income taxes:</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestmentsAbstract" xlink:to="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestmentsAbstract_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestmentsAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments [Abstract]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic" xlink:type="locator" xlink:label="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">United States</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic" xlink:to="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Income Loss From Continuing Operations Before Income Taxes Domestic</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign" xlink:type="locator" xlink:label="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Foreign</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign" xlink:to="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Income Loss From Continuing Operations Before Income Taxes Foreign</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CurrentIncomeTaxExpenseBenefitContinuingOperationsAbstract" xlink:type="locator" xlink:label="us-gaap_CurrentIncomeTaxExpenseBenefitContinuingOperationsAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CurrentIncomeTaxExpenseBenefitContinuingOperationsAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Current taxes:</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CurrentIncomeTaxExpenseBenefitContinuingOperationsAbstract" xlink:to="us-gaap_CurrentIncomeTaxExpenseBenefitContinuingOperationsAbstract_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CurrentIncomeTaxExpenseBenefitContinuingOperationsAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Current Income Tax Expense Benefit Continuing Operations [Abstract]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CurrentFederalTaxExpenseBenefit" xlink:type="locator" xlink:label="us-gaap_CurrentFederalTaxExpenseBenefit" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CurrentFederalTaxExpenseBenefit_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">United States</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CurrentFederalTaxExpenseBenefit" xlink:to="us-gaap_CurrentFederalTaxExpenseBenefit_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CurrentFederalTaxExpenseBenefit_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Current Federal Tax Expense Benefit</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CurrentStateAndLocalTaxExpenseBenefit" xlink:type="locator" xlink:label="us-gaap_CurrentStateAndLocalTaxExpenseBenefit" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CurrentStateAndLocalTaxExpenseBenefit_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">State</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CurrentStateAndLocalTaxExpenseBenefit" xlink:to="us-gaap_CurrentStateAndLocalTaxExpenseBenefit_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CurrentStateAndLocalTaxExpenseBenefit_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Current State And Local Tax Expense Benefit</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CurrentForeignTaxExpenseBenefit" xlink:type="locator" xlink:label="us-gaap_CurrentForeignTaxExpenseBenefit" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CurrentForeignTaxExpenseBenefit_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Foreign</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CurrentForeignTaxExpenseBenefit" xlink:to="us-gaap_CurrentForeignTaxExpenseBenefit_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CurrentForeignTaxExpenseBenefit_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Current Foreign Tax Expense Benefit</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CurrentIncomeTaxExpenseBenefit" xlink:type="locator" xlink:label="us-gaap_CurrentIncomeTaxExpenseBenefit" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CurrentIncomeTaxExpenseBenefit_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Current taxes, Total</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CurrentIncomeTaxExpenseBenefit" xlink:to="us-gaap_CurrentIncomeTaxExpenseBenefit_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CurrentIncomeTaxExpenseBenefit_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Current Income Tax Expense Benefit</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredIncomeTaxExpenseBenefitContinuingOperationsAbstract" xlink:type="locator" xlink:label="us-gaap_DeferredIncomeTaxExpenseBenefitContinuingOperationsAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredIncomeTaxExpenseBenefitContinuingOperationsAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Deferred taxes:</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredIncomeTaxExpenseBenefitContinuingOperationsAbstract" xlink:to="us-gaap_DeferredIncomeTaxExpenseBenefitContinuingOperationsAbstract_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredIncomeTaxExpenseBenefitContinuingOperationsAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Income Tax Expense Benefit Continuing Operations [Abstract]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredFederalIncomeTaxExpenseBenefit" xlink:type="locator" xlink:label="us-gaap_DeferredFederalIncomeTaxExpenseBenefit" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredFederalIncomeTaxExpenseBenefit_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">United States</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredFederalIncomeTaxExpenseBenefit" xlink:to="us-gaap_DeferredFederalIncomeTaxExpenseBenefit_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredFederalIncomeTaxExpenseBenefit_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Federal Income Tax Expense Benefit</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_DeferredStateLocalAndForeignIncomeTaxExpenseBenefit_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">State and Foreign</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_DeferredStateLocalAndForeignIncomeTaxExpenseBenefit_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Deferred State Local And Foreign Income Tax Expense Benefit</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredIncomeTaxExpenseBenefit_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Deferred taxes, Total</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeTaxExpenseBenefit_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Provision for income taxes</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_DeferredTaxAssetsInventoryAndWarrantyReserves" xlink:type="locator" xlink:label="mksi_DeferredTaxAssetsInventoryAndWarrantyReserves" />
    <link:label xml:lang="en-US" xlink:label="mksi_DeferredTaxAssetsInventoryAndWarrantyReserves_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Deferred tax assets inventory and warranty reserves.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_DeferredTaxAssetsInventoryAndWarrantyReserves" xlink:to="mksi_DeferredTaxAssetsInventoryAndWarrantyReserves_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_DeferredTaxAssetsAccruedExpensesAndOtherReserves" xlink:type="locator" xlink:label="mksi_DeferredTaxAssetsAccruedExpensesAndOtherReserves" />
    <link:label xml:lang="en-US" xlink:label="mksi_DeferredTaxAssetsAccruedExpensesAndOtherReserves_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Deferred tax assets accrued expenses and other reserves.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_DeferredTaxAssetsAccruedExpensesAndOtherReserves" xlink:to="mksi_DeferredTaxAssetsAccruedExpensesAndOtherReserves_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_DeferredTaxAssetsLeaseLiability" xlink:type="locator" xlink:label="mksi_DeferredTaxAssetsLeaseLiability" />
    <link:label xml:lang="en-US" xlink:label="mksi_DeferredTaxAssetsLeaseLiability_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Deferred tax assets lease liability.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_DeferredTaxAssetsLeaseLiability" xlink:to="mksi_DeferredTaxAssetsLeaseLiability_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_Deferredtaxassetsutilizationloss" xlink:type="locator" xlink:label="mksi_Deferredtaxassetsutilizationloss" />
    <link:label xml:lang="en-US" xlink:label="mksi_Deferredtaxassetsutilizationloss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Deferred tax assets utilization loss.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_Deferredtaxassetsutilizationloss" xlink:to="mksi_Deferredtaxassetsutilizationloss_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_DeferredTaxLiabilitiesDepreciationAndAmortization" xlink:type="locator" xlink:label="mksi_DeferredTaxLiabilitiesDepreciationAndAmortization" />
    <link:label xml:lang="en-US" xlink:label="mksi_DeferredTaxLiabilitiesDepreciationAndAmortization_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Deferred tax liabilities depreciation and amortization.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_DeferredTaxLiabilitiesDepreciationAndAmortization" xlink:to="mksi_DeferredTaxLiabilitiesDepreciationAndAmortization_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_DeferredTaxLiabilitiesLoanCosts" xlink:type="locator" xlink:label="mksi_DeferredTaxLiabilitiesLoanCosts" />
    <link:label xml:lang="en-US" xlink:label="mksi_DeferredTaxLiabilitiesLoanCosts_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Deferred tax liabilities loan costs.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_DeferredTaxLiabilitiesLoanCosts" xlink:to="mksi_DeferredTaxLiabilitiesLoanCosts_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_DeferredTaxLiabilityRightOfUseAsset" xlink:type="locator" xlink:label="mksi_DeferredTaxLiabilityRightOfUseAsset" />
    <link:label xml:lang="en-US" xlink:label="mksi_DeferredTaxLiabilityRightOfUseAsset_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Deferred tax liability right of use asset.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_DeferredTaxLiabilityRightOfUseAsset" xlink:to="mksi_DeferredTaxLiabilityRightOfUseAsset_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_DeferredTaxLiabilitiesUnrealizedGainLoss" xlink:type="locator" xlink:label="mksi_DeferredTaxLiabilitiesUnrealizedGainLoss" />
    <link:label xml:lang="en-US" xlink:label="mksi_DeferredTaxLiabilitiesUnrealizedGainLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Deferred tax liabilities, unrealized gain / loss.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_DeferredTaxLiabilitiesUnrealizedGainLoss" xlink:to="mksi_DeferredTaxLiabilitiesUnrealizedGainLoss_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_IncomeTaxesDisclosureAbstract" xlink:type="locator" xlink:label="mksi_IncomeTaxesDisclosureAbstract" />
    <link:label xml:lang="en-US" xlink:label="mksi_IncomeTaxesDisclosureAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Income Taxes Disclosure Abstract.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_IncomeTaxesDisclosureAbstract" xlink:to="mksi_IncomeTaxesDisclosureAbstract_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_IncomeTaxesDisclosureAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Income Taxes Disclosure [Abstract]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ComponentsOfDeferredTaxAssetsAbstract" xlink:type="locator" xlink:label="us-gaap_ComponentsOfDeferredTaxAssetsAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ComponentsOfDeferredTaxAssetsAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Deferred tax assets:</link:label>
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    <link:label xml:lang="en-US" xlink:label="mksi_DeferredTaxAssetsAccruedExpensesAndOtherReserves_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accrued expenses and other reserves</link:label>
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    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeBenefits" xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeBenefits" />
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    <link:label xml:lang="en-US" xlink:label="mksi_DeferredTaxAssetsLeaseLiability_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Lease liability</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_DeferredTaxAssetsLeaseLiability_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Tax Assets Lease Liability</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_Deferredtaxassetsutilizationloss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Deferred tax assets utilization loss</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_Deferredtaxassetsutilizationloss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Deferredtaxassetsutilizationloss</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetsOther" xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsOther" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredTaxAssetsOther_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredTaxAssetsOther_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Tax Assets Other</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetsGross" xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsGross" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredTaxAssetsGross_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total deferred tax assets</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredTaxAssetsGross" xlink:to="us-gaap_DeferredTaxAssetsGross_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredTaxAssetsGross_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Tax Assets Gross</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ComponentsOfDeferredTaxLiabilitiesAbstract" xlink:type="locator" xlink:label="us-gaap_ComponentsOfDeferredTaxLiabilitiesAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ComponentsOfDeferredTaxLiabilitiesAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Deferred tax liabilities:</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ComponentsOfDeferredTaxLiabilitiesAbstract" xlink:to="us-gaap_ComponentsOfDeferredTaxLiabilitiesAbstract_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ComponentsOfDeferredTaxLiabilitiesAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Components Of Deferred Tax Liabilities [Abstract]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets" xlink:type="locator" xlink:label="us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Acquired intangible assets and goodwill</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Tax Liabilities Goodwill And Intangible Assets Intangible Assets</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_DeferredTaxLiabilitiesDepreciationAndAmortization_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Depreciation and amortization</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_DeferredTaxLiabilitiesDepreciationAndAmortization_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Tax Liabilities Depreciation And Amortization</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_DeferredTaxLiabilitiesLoanCosts_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Loan costs</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_DeferredTaxLiabilitiesLoanCosts_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Tax Liabilities Loan Costs</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_DeferredTaxLiabilityRightOfUseAsset_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Right-of-use asset</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_DeferredTaxLiabilityRightOfUseAsset_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Tax Liability Right Of Use Asset</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxLiabilitiesUndistributedForeignEarnings" xlink:type="locator" xlink:label="us-gaap_DeferredTaxLiabilitiesUndistributedForeignEarnings" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredTaxLiabilitiesUndistributedForeignEarnings_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Foreign withholding taxes</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredTaxLiabilitiesUndistributedForeignEarnings" xlink:to="us-gaap_DeferredTaxLiabilitiesUndistributedForeignEarnings_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredTaxLiabilitiesUndistributedForeignEarnings_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Tax Liabilities Undistributed Foreign Earnings</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_DeferredTaxLiabilitiesUnrealizedGainLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Unrealized gain</link:label>
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    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredIncomeTaxLiabilities" xlink:type="locator" xlink:label="us-gaap_DeferredIncomeTaxLiabilities" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredIncomeTaxLiabilities_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedTotalLabel">Total deferred tax liabilities</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredIncomeTaxLiabilities_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Income Tax Liabilities</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetsValuationAllowance" xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsValuationAllowance" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredTaxAssetsValuationAllowance_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Valuation allowance</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredTaxAssetsValuationAllowance_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Tax Assets Valuation Allowance</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxLiabilities" xlink:type="locator" xlink:label="us-gaap_DeferredTaxLiabilities" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredTaxLiabilities_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedTotalLabel">Net deferred tax (liabilities) assets</link:label>
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    <link:loc xlink:href="mksi-20211231.xsd#mksi_TaxCreditCarryForwardExpirationYearEnd" xlink:type="locator" xlink:label="mksi_TaxCreditCarryForwardExpirationYearEnd" />
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    <link:loc xlink:href="mksi-20211231.xsd#mksi_IncomeTaxesLineItems" xlink:type="locator" xlink:label="mksi_IncomeTaxesLineItems" />
    <link:label xml:lang="en-US" xlink:label="mksi_IncomeTaxesLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Income Taxes [Line Items].</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_IncomeTaxesLineItems" xlink:to="mksi_IncomeTaxesLineItems_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_IncomeTaxesTableTable" xlink:type="locator" xlink:label="mksi_IncomeTaxesTableTable" />
    <link:label xml:lang="en-US" xlink:label="mksi_IncomeTaxesTableTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Income Taxes [Table].</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeTaxAuthorityAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Income Tax Authority</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeTaxAuthorityDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Income Tax Authority</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeTaxAuthorityDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Income Tax Authority [Domain]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_FederalStateAndForeignMember" xlink:type="locator" xlink:label="mksi_FederalStateAndForeignMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_FederalStateAndForeignMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Federal state and foreign.</link:label>
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    <link:label xml:lang="en-US" xlink:label="mksi_FederalStateAndForeignMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Federal State and Foreign [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_FederalStateAndForeignMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Federal State And Foreign [Member]</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_TaxCreditCarryforwardAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Tax Credit Carryforward</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_TaxCreditCarryforwardAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Tax Credit Carryforward [Axis]</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_TaxCreditCarryforwardNameDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Tax Credit Carryforward Name [Domain]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_IndefiniteMember" xlink:type="locator" xlink:label="mksi_IndefiniteMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_IndefiniteMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Indefinite [Member].</link:label>
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    <link:label xml:lang="en-US" xlink:label="mksi_IndefiniteMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Indefinite [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_IndefiniteMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Indefinite [Member]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_OperatingLossCarryforwardsExpiringTwoThousandSeventeenMember" xlink:type="locator" xlink:label="mksi_OperatingLossCarryforwardsExpiringTwoThousandSeventeenMember" />
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    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_OperatingLossCarryforwardsExpiringTwoThousandSeventeenMember" xlink:to="mksi_OperatingLossCarryforwardsExpiringTwoThousandSeventeenMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_OperatingLossCarryforwardsExpiringTwoThousandSeventeenMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2017 [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_OperatingLossCarryforwardsExpiringTwoThousandSeventeenMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Operating Loss Carryforwards Expiring Two Thousand Seventeen [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeTaxAuthorityNameAxis" xlink:type="locator" xlink:label="us-gaap_IncomeTaxAuthorityNameAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeTaxAuthorityNameAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Income Tax Authority, Name</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeTaxAuthorityNameAxis" xlink:to="us-gaap_IncomeTaxAuthorityNameAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeTaxAuthorityNameAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Income Tax Authority Name [Axis]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeTaxAuthorityNameDomain" xlink:type="locator" xlink:label="us-gaap_IncomeTaxAuthorityNameDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeTaxAuthorityNameDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Income Tax Authority, Name</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeTaxAuthorityNameDomain" xlink:to="us-gaap_IncomeTaxAuthorityNameDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeTaxAuthorityNameDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Income Tax Authority Name [Domain]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InlandRevenueSingaporeIRASMember" xlink:type="locator" xlink:label="us-gaap_InlandRevenueSingaporeIRASMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_InlandRevenueSingaporeIRASMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Inland Revenue, Singapore (IRAS) [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InlandRevenueSingaporeIRASMember" xlink:to="us-gaap_InlandRevenueSingaporeIRASMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_InlandRevenueSingaporeIRASMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Inland Revenue Singapore I R A S [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_IncomeTaxesLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Income Taxes [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_IncomeTaxesLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Income Taxes [Line Items]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TaxCreditCarryforwardAmount" xlink:type="locator" xlink:label="us-gaap_TaxCreditCarryforwardAmount" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TaxCreditCarryforwardAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Gross tax research other tax credit carryforwards</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TaxCreditCarryforwardAmount" xlink:to="us-gaap_TaxCreditCarryforwardAmount_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TaxCreditCarryforwardAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Tax Credit Carryforward Amount</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_TaxCreditCarryForwardExpirationYearEnd_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Tax credit expiration period</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_TaxCreditCarryForwardExpirationYearEnd_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Tax Credit Carry Forward Expiration Year End</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLossCarryforwards" xlink:type="locator" xlink:label="us-gaap_OperatingLossCarryforwards" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLossCarryforwards_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating loss carryforwards</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingLossCarryforwards" xlink:to="us-gaap_OperatingLossCarryforwards_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLossCarryforwards_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Operating Loss Carryforwards</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLossCarryforwardsExpirationDate" xlink:type="locator" xlink:label="us-gaap_OperatingLossCarryforwardsExpirationDate" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLossCarryforwardsExpirationDate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating loss carryforwards expiration date</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingLossCarryforwardsExpirationDate" xlink:to="us-gaap_OperatingLossCarryforwardsExpirationDate_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLossCarryforwardsExpirationDate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Operating Loss Carryforwards Expiration Date</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_UnrecognizedTaxBenefitsIncreaseDecreaseResultingFromPriorPeriodTaxPositions" xlink:type="locator" xlink:label="mksi_UnrecognizedTaxBenefitsIncreaseDecreaseResultingFromPriorPeriodTaxPositions" />
    <link:label xml:lang="en-US" xlink:label="mksi_UnrecognizedTaxBenefitsIncreaseDecreaseResultingFromPriorPeriodTaxPositions_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Unrecognized tax benefits increase decrease resulting from prior period tax positions.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_UnrecognizedTaxBenefitsIncreaseDecreaseResultingFromPriorPeriodTaxPositions" xlink:to="mksi_UnrecognizedTaxBenefitsIncreaseDecreaseResultingFromPriorPeriodTaxPositions_lbl" />
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_UnrecognizedTaxBenefits" xlink:type="locator" xlink:label="us-gaap_UnrecognizedTaxBenefits" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_UnrecognizedTaxBenefits_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Balance at beginning of year</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_UnrecognizedTaxBenefits" xlink:to="us-gaap_UnrecognizedTaxBenefits_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_UnrecognizedTaxBenefits_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Unrecognized Tax Benefits</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_UnrecognizedTaxBenefitsIncreaseDecreaseResultingFromPriorPeriodTaxPositions_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">(Decreases) increases for prior years</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_UnrecognizedTaxBenefitsIncreaseDecreaseResultingFromPriorPeriodTaxPositions_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Unrecognized Tax Benefits Increase Decrease Resulting From Prior Period Tax Positions</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions" xlink:type="locator" xlink:label="us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Increases for the current year</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions" xlink:to="us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations" xlink:type="locator" xlink:label="us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Reductions related to expiration of statutes of limitations and audit settlements</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations" xlink:to="us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Unrecognized Tax Benefits Reductions Resulting From Lapse Of Applicable Statute Of Limitations</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_UnrecognizedTaxBenefits_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Balance at end of year</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued" xlink:type="locator" xlink:label="us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accrued interest on unrecognized tax benefits</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued" xlink:to="us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Unrecognized Tax Benefits Income Tax Penalties And Interest Accrued</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions" xlink:type="locator" xlink:label="us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Net unrecognized tax benefits, excluding interest and penalties, related to foreign tax positions</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions" xlink:to="us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Unrecognized Tax Benefits Increases Resulting From Prior Period Tax Positions</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount" xlink:type="locator" xlink:label="us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Change in valuation allowance</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount" xlink:to="us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Valuation Allowance Deferred Tax Asset Change In Amount</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_BenefitsOfTheTaxHoliday" xlink:type="locator" xlink:label="mksi_BenefitsOfTheTaxHoliday" />
    <link:label xml:lang="en-US" xlink:label="mksi_BenefitsOfTheTaxHoliday_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Benefits of the tax holiday.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_BenefitsOfTheTaxHoliday" xlink:to="mksi_BenefitsOfTheTaxHoliday_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_BenefitsOfTheTaxHoliDayPerShare" xlink:type="locator" xlink:label="mksi_BenefitsOfTheTaxHoliDayPerShare" />
    <link:label xml:lang="en-US" xlink:label="mksi_BenefitsOfTheTaxHoliDayPerShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Benefits of the tax holiday per share.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_BenefitsOfTheTaxHoliDayPerShare" xlink:to="mksi_BenefitsOfTheTaxHoliDayPerShare_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_BenefitsOfTheTaxHoliday_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Benefits of the tax holiday</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_BenefitsOfTheTaxHoliday_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Benefits Of The Tax Holiday</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_BenefitsOfTheTaxHoliDayPerShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Benefits of the tax holiday per share</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_BenefitsOfTheTaxHoliDayPerShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Benefits Of The Tax Holi Day Per Share</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_PercentageOfPayrollDeductionToCompensation" xlink:type="locator" xlink:label="mksi_PercentageOfPayrollDeductionToCompensation" />
    <link:label xml:lang="en-US" xlink:label="mksi_PercentageOfPayrollDeductionToCompensation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Percentage of payroll deduction to compensation.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_PercentageOfPayrollDeductionToCompensation" xlink:to="mksi_PercentageOfPayrollDeductionToCompensation_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_StockExercisePriceAsPercentageOfClosingMarketPrice" xlink:type="locator" xlink:label="mksi_StockExercisePriceAsPercentageOfClosingMarketPrice" />
    <link:label xml:lang="en-US" xlink:label="mksi_StockExercisePriceAsPercentageOfClosingMarketPrice_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Stock exercise price as percentage of closing market price.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_StockExercisePriceAsPercentageOfClosingMarketPrice" xlink:to="mksi_StockExercisePriceAsPercentageOfClosingMarketPrice_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_CommonStockExercisePrice" xlink:type="locator" xlink:label="mksi_CommonStockExercisePrice" />
    <link:label xml:lang="en-US" xlink:label="mksi_CommonStockExercisePrice_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Common stock exercise price.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_CommonStockExercisePrice" xlink:to="mksi_CommonStockExercisePrice_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_MaximumPercentageOfPayrollForPurchaseOfStock" xlink:type="locator" xlink:label="mksi_MaximumPercentageOfPayrollForPurchaseOfStock" />
    <link:label xml:lang="en-US" xlink:label="mksi_MaximumPercentageOfPayrollForPurchaseOfStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Maximum percentage of payroll for purchase of stock</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_MaximumPercentageOfPayrollForPurchaseOfStock" xlink:to="mksi_MaximumPercentageOfPayrollForPurchaseOfStock_lbl" />
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CompensationRelatedCostsAbstract" xlink:type="locator" xlink:label="us-gaap_CompensationRelatedCostsAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CompensationRelatedCostsAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Compensation Related Costs [Abstract]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CompensationRelatedCostsAbstract" xlink:to="us-gaap_CompensationRelatedCostsAbstract_lbl" />
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Table]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Table]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PlanNameAxis" xlink:type="locator" xlink:label="us-gaap_PlanNameAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PlanNameAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Plan Name</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PlanNameAxis" xlink:to="us-gaap_PlanNameAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PlanNameAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Plan Name [Axis]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PlanNameDomain" xlink:type="locator" xlink:label="us-gaap_PlanNameDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PlanNameDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Plan Name</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PlanNameDomain" xlink:to="us-gaap_PlanNameDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PlanNameDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Plan Name [Domain]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_TwoThousandFourteenEmployeeStockPurchasePlanMember" xlink:type="locator" xlink:label="mksi_TwoThousandFourteenEmployeeStockPurchasePlanMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_TwoThousandFourteenEmployeeStockPurchasePlanMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Two thousand fourteen employee stock purchase plan</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_TwoThousandFourteenEmployeeStockPurchasePlanMember" xlink:to="mksi_TwoThousandFourteenEmployeeStockPurchasePlanMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_TwoThousandFourteenEmployeeStockPurchasePlanMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2014 ESPP [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_TwoThousandFourteenEmployeeStockPurchasePlanMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Two Thousand Fourteen Employee Stock Purchase Plan [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Exercise Price Range</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis" xlink:to="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Shares Authorized Under Stock Option Plans By Exercise Price Range [Axis]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Exercise Price Range</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:to="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Domain]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_OfferTerminateMember" xlink:type="locator" xlink:label="mksi_OfferTerminateMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_OfferTerminateMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">OfferTerminate Member.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_OfferTerminateMember" xlink:to="mksi_OfferTerminateMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_OfferTerminateMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Offer Terminate [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_OfferTerminateMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Offer Terminate [Member]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_StockIncentivePlanTwoThousandFourteenMember" xlink:type="locator" xlink:label="mksi_StockIncentivePlanTwoThousandFourteenMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_StockIncentivePlanTwoThousandFourteenMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Stock Incentive Plan Two Thousand Fourteen</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_StockIncentivePlanTwoThousandFourteenMember" xlink:to="mksi_StockIncentivePlanTwoThousandFourteenMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_StockIncentivePlanTwoThousandFourteenMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Stock Incentive Plan 2014 [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_StockIncentivePlanTwoThousandFourteenMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stock Incentive Plan Two Thousand Fourteen [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AwardTypeAxis" xlink:type="locator" xlink:label="us-gaap_AwardTypeAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AwardTypeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Award Type</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AwardTypeAxis" xlink:to="us-gaap_AwardTypeAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AwardTypeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Award Type [Axis]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Award Type</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangements By Share Based Payment Award Award Type And Plan Name [Domain]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember" xlink:type="locator" xlink:label="us-gaap_RestrictedStockUnitsRSUMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RestrictedStockUnitsRSUMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Restricted Stock Units (RSUs) [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RestrictedStockUnitsRSUMember" xlink:to="us-gaap_RestrictedStockUnitsRSUMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RestrictedStockUnitsRSUMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Restricted Stock Units R S U [Member]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_RestrictedStockUnitsGrantedToEmployeesMember" xlink:type="locator" xlink:label="mksi_RestrictedStockUnitsGrantedToEmployeesMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_RestrictedStockUnitsGrantedToEmployeesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Restricted Stock Units Granted To Employees [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_RestrictedStockUnitsGrantedToEmployeesMember" xlink:to="mksi_RestrictedStockUnitsGrantedToEmployeesMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_RestrictedStockUnitsGrantedToEmployeesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">RSUs Granted to Employees [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_RestrictedStockUnitsGrantedToEmployeesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Restricted Stock Units Granted To Employees [Member]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_RestrictedStockUnitsGrantedToDirectorsMember" xlink:type="locator" xlink:label="mksi_RestrictedStockUnitsGrantedToDirectorsMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_RestrictedStockUnitsGrantedToDirectorsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">RSU granted to directors.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_RestrictedStockUnitsGrantedToDirectorsMember" xlink:to="mksi_RestrictedStockUnitsGrantedToDirectorsMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_RestrictedStockUnitsGrantedToDirectorsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">RSUs Granted To Directors [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_RestrictedStockUnitsGrantedToDirectorsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Restricted Stock Units Granted To Directors [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_VestingAxis" xlink:type="locator" xlink:label="us-gaap_VestingAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_VestingAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Vesting</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_VestingAxis" xlink:to="us-gaap_VestingAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_VestingAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Vesting [Axis]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_VestingDomain" xlink:type="locator" xlink:label="us-gaap_VestingDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_VestingDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Vesting</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_VestingDomain" xlink:to="us-gaap_VestingDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_VestingDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Vesting [Domain]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationAwardTrancheOneMember" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationAwardTrancheOneMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationAwardTrancheOneMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Share-based Compensation Award, Tranche One [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationAwardTrancheOneMember" xlink:to="us-gaap_ShareBasedCompensationAwardTrancheOneMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationAwardTrancheOneMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Award Tranche One [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Share Based Compensation Arrangement By Share Based Payment Award [Line Items]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award [Line Items]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredCompensationArrangementWithIndividualSharesAuthorizedForIssuance" xlink:type="locator" xlink:label="us-gaap_DeferredCompensationArrangementWithIndividualSharesAuthorizedForIssuance" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredCompensationArrangementWithIndividualSharesAuthorizedForIssuance_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Shares authorized for issuance</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredCompensationArrangementWithIndividualSharesAuthorizedForIssuance" xlink:to="us-gaap_DeferredCompensationArrangementWithIndividualSharesAuthorizedForIssuance_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredCompensationArrangementWithIndividualSharesAuthorizedForIssuance_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Compensation Arrangement With Individual Shares Authorized For Issuance</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_PercentageOfPayrollDeductionToCompensation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Percentage of payroll deduction to compensation</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_PercentageOfPayrollDeductionToCompensation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Percentage Of Payroll Deduction To Compensation</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_MaximumPercentageOfPayrollForPurchaseOfStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Percentage of Common Stock through payroll deductions</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_MaximumPercentageOfPayrollForPurchaseOfStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Maximum Percentage Of Payroll For Purchase Of Stock</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_StockExercisePriceAsPercentageOfClosingMarketPrice_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Percentage of closing price of the Common Stock</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_StockExercisePriceAsPercentageOfClosingMarketPrice_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stock Exercise Price As Percentage Of Closing Market Price</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_CommonStockExercisePrice_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common stock, exercise price</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_CommonStockExercisePrice_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock Exercise Price</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockCapitalSharesReservedForFutureIssuance" xlink:type="locator" xlink:label="us-gaap_CommonStockCapitalSharesReservedForFutureIssuance" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common stock reserved for issuance</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommonStockCapitalSharesReservedForFutureIssuance" xlink:to="us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock Capital Shares Reserved For Future Issuance</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_NumberOfSharesReturnedForEachShareOfCommonStock" xlink:type="locator" xlink:label="mksi_NumberOfSharesReturnedForEachShareOfCommonStock" />
    <link:label xml:lang="en-US" xlink:label="mksi_NumberOfSharesReturnedForEachShareOfCommonStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Number Of Shares Returned For Each Share Of Common Stock</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_NumberOfSharesReturnedForEachShareOfCommonStock" xlink:to="mksi_NumberOfSharesReturnedForEachShareOfCommonStock_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodPercentageExercisePrice" xlink:type="locator" xlink:label="mksi_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodPercentageExercisePrice" />
    <link:label xml:lang="en-US" xlink:label="mksi_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodPercentageExercisePrice_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Percentage of the balance sheet date at which grantees can acquire the shares reserved for issuance on stock options awarded under the plan during the reporting period.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodPercentageExercisePrice" xlink:to="mksi_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodPercentageExercisePrice_lbl" />
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Shares available for future grant</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Available For Grant</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_NumberOfSharesReturnedForEachShareOfCommonStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Number of shares returned for each common stock</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_NumberOfSharesReturnedForEachShareOfCommonStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Number Of Shares Returned For Each Share Of Common Stock</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodPercentageExercisePrice_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Percentage of exercise price fair value option grant in period</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodPercentageExercisePrice_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Percentage Exercise Price</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_LevelOfPerformanceTargetAchievedPercentage" xlink:type="locator" xlink:label="mksi_LevelOfPerformanceTargetAchievedPercentage" />
    <link:label xml:lang="en-US" xlink:label="mksi_LevelOfPerformanceTargetAchievedPercentage_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Level of performance target achieved percentage.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_LevelOfPerformanceTargetAchievedPercentage" xlink:to="mksi_LevelOfPerformanceTargetAchievedPercentage_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_ShareBasedCompensationArrangementByShareBasedPaymentAwardVestingPeriodDescription" xlink:type="locator" xlink:label="mksi_ShareBasedCompensationArrangementByShareBasedPaymentAwardVestingPeriodDescription" />
    <link:label xml:lang="en-US" xlink:label="mksi_ShareBasedCompensationArrangementByShareBasedPaymentAwardVestingPeriodDescription_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Share based compensation arrangement by share based payment award vesting period description.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_ShareBasedCompensationArrangementByShareBasedPaymentAwardVestingPeriodDescription" xlink:to="mksi_ShareBasedCompensationArrangementByShareBasedPaymentAwardVestingPeriodDescription_lbl" />
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage" xlink:type="locator" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Vesting percentage per year of RSUs from date of grant</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Sharebased Compensation Arrangement By Sharebased Payment Award Award Vesting Rights Percentage</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_LevelOfPerformanceTargetAchievedPercentage_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Level of performance target achieved</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_LevelOfPerformanceTargetAchievedPercentage_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Level Of Performance Target Achieved Percentage</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_ShareBasedCompensationArrangementByShareBasedPaymentAwardVestingPeriodDescription_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Share based compensation arrangement by share based payment award vesting period description</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_ShareBasedCompensationArrangementByShareBasedPaymentAwardVestingPeriodDescription_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Vesting Period Description</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">RSUs, beginning of period</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/positiveTerseLabel">Granted</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Vested</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">RSUs end of period</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">RSUs, Weighted Average Grant Date Fair Value, Beginning of period</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Weighted Average Grant Date Fair Value, Granted</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Weighted Average Grant Date Fair Value</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Weighted Average Grant Date Fair Value, Vested</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Weighted Average Grant Date Fair Value</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">RSUs, Weighted Average Grant Date Fair Value, end of period</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_AllocatedShareBasedCompensationEffectOnEarningPerShareBasic" xlink:type="locator" xlink:label="mksi_AllocatedShareBasedCompensationEffectOnEarningPerShareBasic" />
    <link:label xml:lang="en-US" xlink:label="mksi_AllocatedShareBasedCompensationEffectOnEarningPerShareBasic_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Allocated share based compensation effect on earning per share basic.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_AllocatedShareBasedCompensationEffectOnEarningPerShareBasic" xlink:to="mksi_AllocatedShareBasedCompensationEffectOnEarningPerShareBasic_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_AllocatedShareBasedCompensationEffectOnEarningPerShareDiluted" xlink:type="locator" xlink:label="mksi_AllocatedShareBasedCompensationEffectOnEarningPerShareDiluted" />
    <link:label xml:lang="en-US" xlink:label="mksi_AllocatedShareBasedCompensationEffectOnEarningPerShareDiluted_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Allocated share based compensation effect on earning per share diluted.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_AllocatedShareBasedCompensationEffectOnEarningPerShareDiluted" xlink:to="mksi_AllocatedShareBasedCompensationEffectOnEarningPerShareDiluted_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_EmployeeStockPurchasePlanMember" xlink:type="locator" xlink:label="mksi_EmployeeStockPurchasePlanMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_EmployeeStockPurchasePlanMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Employee stock purchase plan [member].</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_EmployeeStockPurchasePlanMember" xlink:to="mksi_EmployeeStockPurchasePlanMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_EmployeeStockPurchasePlanMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Employee Stock Purchase Plan [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_EmployeeStockPurchasePlanMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Employee Stock Purchase Plan [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense" xlink:type="locator" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Windfall tax effect on stock-based compensation</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense" xlink:to="us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Employee Service Share Based Compensation Tax Benefit From Compensation Expense</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpenseNetOfTax" xlink:type="locator" xlink:label="us-gaap_AllocatedShareBasedCompensationExpenseNetOfTax" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AllocatedShareBasedCompensationExpenseNetOfTax_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Net effect on net income</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AllocatedShareBasedCompensationExpenseNetOfTax" xlink:to="us-gaap_AllocatedShareBasedCompensationExpenseNetOfTax_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AllocatedShareBasedCompensationExpenseNetOfTax_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Allocated Share Based Compensation Expense Net Of Tax</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_AllocatedShareBasedCompensationEffectOnEarningPerShareBasic_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Basic</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_AllocatedShareBasedCompensationEffectOnEarningPerShareBasic_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Allocated Share Based Compensation Effect On Earning Per Share Basic</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_AllocatedShareBasedCompensationEffectOnEarningPerShareDiluted_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Diluted</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_AllocatedShareBasedCompensationEffectOnEarningPerShareDiluted_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Allocated Share Based Compensation Effect On Earning Per Share Diluted</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule Of Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Table]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable" xlink:to="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Table]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CostOfSalesMember" xlink:type="locator" xlink:label="us-gaap_CostOfSalesMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CostOfSalesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Cost of Revenues [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CostOfSalesMember" xlink:to="us-gaap_CostOfSalesMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CostOfSalesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Cost Of Sales [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ResearchAndDevelopmentExpenseMember" xlink:type="locator" xlink:label="us-gaap_ResearchAndDevelopmentExpenseMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ResearchAndDevelopmentExpenseMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Research and Development [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ResearchAndDevelopmentExpenseMember" xlink:to="us-gaap_ResearchAndDevelopmentExpenseMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ResearchAndDevelopmentExpenseMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Research And Development Expense [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SellingGeneralAndAdministrativeExpensesMember" xlink:type="locator" xlink:label="us-gaap_SellingGeneralAndAdministrativeExpensesMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SellingGeneralAndAdministrativeExpensesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Selling, General and Administrative [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SellingGeneralAndAdministrativeExpensesMember" xlink:to="us-gaap_SellingGeneralAndAdministrativeExpensesMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SellingGeneralAndAdministrativeExpensesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Selling General And Administrative Expenses [Member]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_AcquisitionAndIntegrationCostMember" xlink:type="locator" xlink:label="mksi_AcquisitionAndIntegrationCostMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_AcquisitionAndIntegrationCostMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Acquisition and integration cost.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_AcquisitionAndIntegrationCostMember" xlink:to="mksi_AcquisitionAndIntegrationCostMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_AcquisitionAndIntegrationCostMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Acquisition and Integration Cost [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_AcquisitionAndIntegrationCostMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Acquisition And Integration Cost [Member]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_RestructuringExpenseMember" xlink:type="locator" xlink:label="mksi_RestructuringExpenseMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_RestructuringExpenseMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Restructuring expense.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_RestructuringExpenseMember" xlink:to="mksi_RestructuringExpenseMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_RestructuringExpenseMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Restructuring Related Expense [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_RestructuringExpenseMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Restructuring Expense [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" xlink:type="locator" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" xlink:to="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendPerShare" xlink:type="locator" xlink:label="mksi_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendPerShare" />
    <link:label xml:lang="en-US" xlink:label="mksi_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendPerShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Share based compensation arrangement by share based payment award fair value assumptions expected dividend per share.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendPerShare" xlink:to="mksi_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendPerShare_lbl" />
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" xlink:type="locator" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Expected life (years)</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Sharebased Compensation Arrangement By Sharebased Payment Award Fair Value Assumptions Expected Term1</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Risk-free interest rate</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Risk Free Interest Rate</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Expected volatility</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Volatility Rate</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendPerShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Expected annual dividends per share</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendPerShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Dividend Per Share</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1" xlink:type="locator" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Total fair value of RSUs vested</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested In Period Fair Value1</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" xlink:type="locator" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Total compensation expense related to restricted stock unites</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" xlink:to="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:type="locator" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Estimated weighted average amortization period</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:to="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Period For Recognition1</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityAbstract" xlink:type="locator" xlink:label="us-gaap_EquityAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EquityAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Equity [Abstract]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EquityAbstract" xlink:to="us-gaap_EquityAbstract_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_StockholdersEquityLineItems" xlink:type="locator" xlink:label="mksi_StockholdersEquityLineItems" />
    <link:label xml:lang="en-US" xlink:label="mksi_StockholdersEquityLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Stockholders Equity [Line Items]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_StockholdersEquityLineItems" xlink:to="mksi_StockholdersEquityLineItems_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_StockholdersEquityTable" xlink:type="locator" xlink:label="mksi_StockholdersEquityTable" />
    <link:label xml:lang="en-US" xlink:label="mksi_StockholdersEquityTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Stockholders Equity [Table]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_StockholdersEquityTable" xlink:to="mksi_StockholdersEquityTable_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_StockholdersEquityTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Stockholders Equity [Table]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_StockholdersEquityTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stockholders Equity [Table]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:type="locator" xlink:label="us-gaap_SubsequentEventTypeAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SubsequentEventTypeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Subsequent Event Type</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SubsequentEventTypeAxis" xlink:to="us-gaap_SubsequentEventTypeAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SubsequentEventTypeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Subsequent Event Type [Axis]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:type="locator" xlink:label="us-gaap_SubsequentEventTypeDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SubsequentEventTypeDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Subsequent Event Type</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SubsequentEventTypeDomain" xlink:to="us-gaap_SubsequentEventTypeDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SubsequentEventTypeDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Subsequent Event Type [Domain]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventMember" xlink:type="locator" xlink:label="us-gaap_SubsequentEventMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SubsequentEventMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Subsequent Event [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SubsequentEventMember" xlink:to="us-gaap_SubsequentEventMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SubsequentEventMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Subsequent Event [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_StockholdersEquityLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Stockholders Equity [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_StockholdersEquityLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stockholders Equity [Line Items]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockRepurchaseProgramAuthorizedAmount1" xlink:type="locator" xlink:label="us-gaap_StockRepurchaseProgramAuthorizedAmount1" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockRepurchaseProgramAuthorizedAmount1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common stock, value of shares authorized to repurchase</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockRepurchaseProgramAuthorizedAmount1" xlink:to="us-gaap_StockRepurchaseProgramAuthorizedAmount1_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockRepurchaseProgramAuthorizedAmount1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stock Repurchase Program Authorized Amount1</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockRepurchasedDuringPeriodShares" xlink:type="locator" xlink:label="us-gaap_StockRepurchasedDuringPeriodShares" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockRepurchasedDuringPeriodShares_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Stock repurchase, shares</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockRepurchasedDuringPeriodShares" xlink:to="us-gaap_StockRepurchasedDuringPeriodShares_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockRepurchasedDuringPeriodShares_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stock Repurchased During Period Shares</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockRepurchasedDuringPeriodValue" xlink:type="locator" xlink:label="us-gaap_StockRepurchasedDuringPeriodValue" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockRepurchasedDuringPeriodValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Value of shares repurchased</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockRepurchasedDuringPeriodValue" xlink:to="us-gaap_StockRepurchasedDuringPeriodValue_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockRepurchasedDuringPeriodValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stock Repurchased During Period Value</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockDividendsPerShareCashPaid" xlink:type="locator" xlink:label="us-gaap_CommonStockDividendsPerShareCashPaid" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CommonStockDividendsPerShareCashPaid_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Cash dividends per common share</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommonStockDividendsPerShareCashPaid" xlink:to="us-gaap_CommonStockDividendsPerShareCashPaid_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CommonStockDividendsPerShareCashPaid_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock Dividends Per Share Cash Paid</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_PaymentsOfDividendsCommonStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Dividend payment to common shareholders</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DividendsPayableDateDeclaredDayMonthAndYear" xlink:type="locator" xlink:label="us-gaap_DividendsPayableDateDeclaredDayMonthAndYear" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DividendsPayableDateDeclaredDayMonthAndYear_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Dividend declared date</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DividendsPayableDateDeclaredDayMonthAndYear" xlink:to="us-gaap_DividendsPayableDateDeclaredDayMonthAndYear_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DividendsPayableDateDeclaredDayMonthAndYear_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Dividends Payable Date Declared Day Month And Year</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DividendsPayableAmountPerShare" xlink:type="locator" xlink:label="us-gaap_DividendsPayableAmountPerShare" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DividendsPayableAmountPerShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Cash dividend to be paid</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DividendsPayableAmountPerShare" xlink:to="us-gaap_DividendsPayableAmountPerShare_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DividendsPayableAmountPerShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Dividends Payable Amount Per Share</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DividendPayableDateToBePaidDayMonthAndYear" xlink:type="locator" xlink:label="us-gaap_DividendPayableDateToBePaidDayMonthAndYear" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DividendPayableDateToBePaidDayMonthAndYear_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Dividend to be paid date</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DividendPayableDateToBePaidDayMonthAndYear" xlink:to="us-gaap_DividendPayableDateToBePaidDayMonthAndYear_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DividendPayableDateToBePaidDayMonthAndYear_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Dividend Payable Date To Be Paid Day Month And Year</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DividendsPayableDateOfRecordDayMonthAndYear" xlink:type="locator" xlink:label="us-gaap_DividendsPayableDateOfRecordDayMonthAndYear" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DividendsPayableDateOfRecordDayMonthAndYear_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Dividend declared, shareholders of record date</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DividendsPayableDateOfRecordDayMonthAndYear" xlink:to="us-gaap_DividendsPayableDateOfRecordDayMonthAndYear_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DividendsPayableDateOfRecordDayMonthAndYear_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Dividends Payable Date Of Record Day Month And Year</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_DefinedContributionPlanMinimumAnnualContributionsPerEmployeePercent" xlink:type="locator" xlink:label="mksi_DefinedContributionPlanMinimumAnnualContributionsPerEmployeePercent" />
    <link:label xml:lang="en-US" xlink:label="mksi_DefinedContributionPlanMinimumAnnualContributionsPerEmployeePercent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Defined Contribution Plan Minimum Annual Contributions Per Employee Percent</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_DefinedContributionPlanMinimumAnnualContributionsPerEmployeePercent" xlink:to="mksi_DefinedContributionPlanMinimumAnnualContributionsPerEmployeePercent_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_MinimumAgeLimitForSpecifiedAdditionalAmount" xlink:type="locator" xlink:label="mksi_MinimumAgeLimitForSpecifiedAdditionalAmount" />
    <link:label xml:lang="en-US" xlink:label="mksi_MinimumAgeLimitForSpecifiedAdditionalAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Minimum age limit for specified additional amount.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_MinimumAgeLimitForSpecifiedAdditionalAmount" xlink:to="mksi_MinimumAgeLimitForSpecifiedAdditionalAmount_lbl" />
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CompensationAndRetirementDisclosureAbstract" xlink:type="locator" xlink:label="us-gaap_CompensationAndRetirementDisclosureAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CompensationAndRetirementDisclosureAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Compensation And Retirement Disclosure [Abstract]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CompensationAndRetirementDisclosureAbstract" xlink:to="us-gaap_CompensationAndRetirementDisclosureAbstract_lbl" />
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule Of Defined Benefit Plans Disclosures [Table]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:to="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Defined Benefit Plans Disclosures [Table]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_StatementScenarioAxis" xlink:type="locator" xlink:label="srt_StatementScenarioAxis" />
    <link:label xml:lang="en-US" xlink:label="srt_StatementScenarioAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Scenario</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_StatementScenarioAxis" xlink:to="srt_StatementScenarioAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="srt_StatementScenarioAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Statement Scenario [Axis]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ScenarioUnspecifiedDomain" xlink:type="locator" xlink:label="srt_ScenarioUnspecifiedDomain" />
    <link:label xml:lang="en-US" xlink:label="srt_ScenarioUnspecifiedDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Scenario</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_ScenarioUnspecifiedDomain" xlink:to="srt_ScenarioUnspecifiedDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="srt_ScenarioUnspecifiedDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Scenario Unspecified [Domain]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ScenarioForecastMember" xlink:type="locator" xlink:label="srt_ScenarioForecastMember" />
    <link:label xml:lang="en-US" xlink:label="srt_ScenarioForecastMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Forecast [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_ScenarioForecastMember" xlink:to="srt_ScenarioForecastMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="srt_ScenarioForecastMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Scenario Forecast [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RetirementPlanTypeAxis" xlink:type="locator" xlink:label="us-gaap_RetirementPlanTypeAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RetirementPlanTypeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Retirement Plan Type</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RetirementPlanTypeAxis" xlink:to="us-gaap_RetirementPlanTypeAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RetirementPlanTypeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Retirement Plan Type [Axis]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RetirementPlanTypeDomain" xlink:type="locator" xlink:label="us-gaap_RetirementPlanTypeDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RetirementPlanTypeDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Retirement Plan Type</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RetirementPlanTypeDomain" xlink:to="us-gaap_RetirementPlanTypeDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RetirementPlanTypeDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Retirement Plan Type [Domain]</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/country/2021/country-2021.xsd#country_IL" xlink:type="locator" xlink:label="country_IL" />
    <link:label xml:lang="en-US" xlink:label="country_IL_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Israel [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="country_IL" xlink:to="country_IL_lbl" />
    <link:label xml:lang="en-US" xlink:label="country_IL_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">ISRAEL</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/country/2021/country-2021.xsd#country_DE" xlink:type="locator" xlink:label="country_DE" />
    <link:label xml:lang="en-US" xlink:label="country_DE_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Germany [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="country_DE" xlink:to="country_DE_lbl" />
    <link:label xml:lang="en-US" xlink:label="country_DE_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">GERMANY</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanDisclosureLineItems" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanDisclosureLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Defined Benefit Plan Disclosure [Line Items]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_DefinedBenefitPlanDisclosureLineItems_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanDisclosureLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Benefit Plan Disclosure [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_DefinedContributionPlanMinimumAnnualContributionsPerEmployeePercent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Employee contribution to Company&apos;s profit sharing plan percentage</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_DefinedContributionPlanMinimumAnnualContributionsPerEmployeePercent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Contribution Plan Minimum Annual Contributions Per Employee Percent</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeePercent" xlink:type="locator" xlink:label="us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeePercent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeePercent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Employee contribution to Company&apos;s profit sharing plan percentage</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeePercent" xlink:to="us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeePercent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeePercent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Contribution Plan Maximum Annual Contributions Per Employee Percent</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_MinimumAgeLimitForSpecifiedAdditionalAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Minimum age limit for specified additional amount</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_MinimumAgeLimitForSpecifiedAdditionalAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Minimum Age Limit For Specified Additional Amount</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PensionAndOtherPostretirementBenefitContributions" xlink:type="locator" xlink:label="us-gaap_PensionAndOtherPostretirementBenefitContributions" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PensionAndOtherPostretirementBenefitContributions_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Company&apos;s contributions</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PensionAndOtherPostretirementBenefitContributions" xlink:to="us-gaap_PensionAndOtherPostretirementBenefitContributions_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PensionAndOtherPostretirementBenefitContributions_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Pension And Other Postretirement Benefit Contributions</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_EmployeePerformanceAwardBonusExpense" xlink:type="locator" xlink:label="mksi_EmployeePerformanceAwardBonusExpense" />
    <link:label xml:lang="en-US" xlink:label="mksi_EmployeePerformanceAwardBonusExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Employee bonus expense (includes bonus expense and performance awards).</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_EmployeePerformanceAwardBonusExpense" xlink:to="mksi_EmployeePerformanceAwardBonusExpense_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_EmployeePerformanceAwardBonusExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Bonus expense</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_EmployeePerformanceAwardBonusExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Employee Performance Award Bonus Expense</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_SupplementalRetirementBenefitsCost" xlink:type="locator" xlink:label="mksi_SupplementalRetirementBenefitsCost" />
    <link:label xml:lang="en-US" xlink:label="mksi_SupplementalRetirementBenefitsCost_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Supplemental retirement benefits cost.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_SupplementalRetirementBenefitsCost" xlink:to="mksi_SupplementalRetirementBenefitsCost_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_SupplementalRetirementBenefitsAccumulatedBenefitObligationNoncurrent" xlink:type="locator" xlink:label="mksi_SupplementalRetirementBenefitsAccumulatedBenefitObligationNoncurrent" />
    <link:label xml:lang="en-US" xlink:label="mksi_SupplementalRetirementBenefitsAccumulatedBenefitObligationNoncurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Supplemental retirement benefits accumulated benefit obligation noncurrent.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_SupplementalRetirementBenefitsAccumulatedBenefitObligationNoncurrent" xlink:to="mksi_SupplementalRetirementBenefitsAccumulatedBenefitObligationNoncurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_SupplementalRetirementBenefitsCost_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Supplemental retirement benefits cost</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_SupplementalRetirementBenefitsCost_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Supplemental Retirement Benefits Cost</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_SupplementalRetirementBenefitsAccumulatedBenefitObligationNoncurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accumulated benefit obligation noncurrent</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_SupplementalRetirementBenefitsAccumulatedBenefitObligationNoncurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Supplemental Retirement Benefits Accumulated Benefit Obligation Noncurrent</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_DefinedBenefitPlanAmortizationOfActuarialGainLoss" xlink:type="locator" xlink:label="mksi_DefinedBenefitPlanAmortizationOfActuarialGainLoss" />
    <link:label xml:lang="en-US" xlink:label="mksi_DefinedBenefitPlanAmortizationOfActuarialGainLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Defined benefit plan amortization of actuarial gain loss.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_DefinedBenefitPlanAmortizationOfActuarialGainLoss" xlink:to="mksi_DefinedBenefitPlanAmortizationOfActuarialGainLoss_lbl" />
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Benefit Plan Net Periodic Benefit Cost [Abstract]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract" xlink:to="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract_lbl" />
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanServiceCost" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanServiceCost" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanServiceCost_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Service cost</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanServiceCost" xlink:to="us-gaap_DefinedBenefitPlanServiceCost_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanServiceCost_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Benefit Plan Service Cost</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanInterestCost" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanInterestCost" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanInterestCost_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Interest cost on projected benefit obligations</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanInterestCost" xlink:to="us-gaap_DefinedBenefitPlanInterestCost_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanInterestCost_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Benefit Plan Interest Cost</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Expected return on plan assets</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets" xlink:to="us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Benefit Plan Expected Return On Plan Assets</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_DefinedBenefitPlanAmortizationOfActuarialGainLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Amortization of actuarial net loss</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_DefinedBenefitPlanAmortizationOfActuarialGainLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Benefit Plan Amortization Of Actuarial Gain Loss</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Net periodic benefit costs</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost" xlink:to="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Benefit Plan Net Periodic Benefit Cost</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_DefinedBenefitPlanPensionPlanChangeInBenefitObligationAbstract" xlink:type="locator" xlink:label="mksi_DefinedBenefitPlanPensionPlanChangeInBenefitObligationAbstract" />
    <link:label xml:lang="en-US" xlink:label="mksi_DefinedBenefitPlanPensionPlanChangeInBenefitObligationAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Defined Benefit Plan Pension Plan Change In Benefit Obligation [Abstract]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_DefinedBenefitPlanPensionPlanChangeInBenefitObligationAbstract" xlink:to="mksi_DefinedBenefitPlanPensionPlanChangeInBenefitObligationAbstract_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_DefinedBenefitPlanPensionPlanChangeInBenefitObligationAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Change in projected benefit obligations:</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_DefinedBenefitPlanPensionPlanChangeInBenefitObligationAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Benefit Plan Pension Plan Change In Benefit Obligation [Abstract]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanBenefitObligation" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanBenefitObligation" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanBenefitObligation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Projected benefit obligations, beginning of year</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanBenefitObligation" xlink:to="us-gaap_DefinedBenefitPlanBenefitObligation_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanBenefitObligation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Benefit Plan Benefit Obligation</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanInterestCost_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Interest cost</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanBenefitObligationContributionsByPlanParticipant" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanBenefitObligationContributionsByPlanParticipant" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanBenefitObligationContributionsByPlanParticipant_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Contributions by plan participants</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanBenefitObligationContributionsByPlanParticipant" xlink:to="us-gaap_DefinedBenefitPlanBenefitObligationContributionsByPlanParticipant_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanBenefitObligationContributionsByPlanParticipant_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Benefit Plan Benefit Obligation Contributions By Plan Participant</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanPlanAmendments" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanPlanAmendments" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanPlanAmendments_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Plan amendments</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanPlanAmendments" xlink:to="us-gaap_DefinedBenefitPlanPlanAmendments_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanPlanAmendments_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Benefit Plan Plan Amendments</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanActuarialGainLoss" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanActuarialGainLoss" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanActuarialGainLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Actuarial loss</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanActuarialGainLoss" xlink:to="us-gaap_DefinedBenefitPlanActuarialGainLoss_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanActuarialGainLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Benefit Plan Actuarial Gain Loss</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Benefits paid</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid" xlink:to="us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Benefit Plan Benefit Obligation Benefits Paid</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesBenefitObligation" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesBenefitObligation" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesBenefitObligation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Currency translation adjustments</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesBenefitObligation" xlink:to="us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesBenefitObligation_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesBenefitObligation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Benefit Plan Foreign Currency Exchange Rate Changes Benefit Obligation</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanBenefitObligation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Projected benefit obligations, end of year</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Change in plan assets:</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward" xlink:to="us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Benefit Plan Change In Fair Value Of Plan Assets Roll Forward</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanFairValueOfPlanAssets" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanFairValueOfPlanAssets" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Fair value of plan assets, beginning of year</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanFairValueOfPlanAssets" xlink:to="us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Benefit Plan Fair Value Of Plan Assets</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanContributionsByEmployer" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanContributionsByEmployer" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanContributionsByEmployer_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Company contributions</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanContributionsByEmployer" xlink:to="us-gaap_DefinedBenefitPlanContributionsByEmployer_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanContributionsByEmployer_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Benefit Plan Contributions By Employer</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">(Loss) gain on plan assets</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets" xlink:to="us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Benefit Plan Actual Return On Plan Assets</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanPlanAssetsBenefitsPaid" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanPlanAssetsBenefitsPaid" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanPlanAssetsBenefitsPaid_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Benefits paid</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanPlanAssetsBenefitsPaid" xlink:to="us-gaap_DefinedBenefitPlanPlanAssetsBenefitsPaid_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanPlanAssetsBenefitsPaid_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Benefit Plan Plan Assets Benefits Paid</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanPlanAssetsForeignCurrencyTranslationGainLoss" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanPlanAssetsForeignCurrencyTranslationGainLoss" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanPlanAssetsForeignCurrencyTranslationGainLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Currency translation adjustments</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanPlanAssetsForeignCurrencyTranslationGainLoss" xlink:to="us-gaap_DefinedBenefitPlanPlanAssetsForeignCurrencyTranslationGainLoss_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanPlanAssetsForeignCurrencyTranslationGainLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Benefit Plan Plan Assets Foreign Currency Translation Gain Loss</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Fair value of plan assets, end of year</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanFundedStatusOfPlan" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanFundedStatusOfPlan" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanFundedStatusOfPlan_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Net underfunded status</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanFundedStatusOfPlan" xlink:to="us-gaap_DefinedBenefitPlanFundedStatusOfPlan_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanFundedStatusOfPlan_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Benefit Plan Funded Status Of Plan</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearSixToTen" xlink:type="locator" xlink:label="mksi_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearSixToTen" />
    <link:label xml:lang="en-US" xlink:label="mksi_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearSixToTen_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Defined benefit plan expected future benefit payments year six to ten.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearSixToTen" xlink:to="mksi_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearSixToTen_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_DefinedBenefitPlanExpectedFutureBenefitPaymentsForNextTenYears" xlink:type="locator" xlink:label="mksi_DefinedBenefitPlanExpectedFutureBenefitPaymentsForNextTenYears" />
    <link:label xml:lang="en-US" xlink:label="mksi_DefinedBenefitPlanExpectedFutureBenefitPaymentsForNextTenYears_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Defined benefit plan expected future benefit payments for next ten years.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_DefinedBenefitPlanExpectedFutureBenefitPaymentsForNextTenYears" xlink:to="mksi_DefinedBenefitPlanExpectedFutureBenefitPaymentsForNextTenYears_lbl" />
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Benefit Plan Estimated Future Benefit Payments [Abstract]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract" xlink:to="us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract_lbl" />
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2022</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths" xlink:to="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Benefit Plan Expected Future Benefit Payments Next Twelve Months</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2023</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo" xlink:to="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Benefit Plan Expected Future Benefit Payments Year Two</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2024</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree" xlink:to="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Benefit Plan Expected Future Benefit Payments Year Three</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2025</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour" xlink:to="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Benefit Plan Expected Future Benefit Payments Year Four</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2026</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive" xlink:to="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Benefit Plan Expected Future Benefit Payments Year Five</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearSixToTen_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2027-2031</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearSixToTen_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Benefit Plan Expected Future Benefit Payments Year Six To Ten</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_DefinedBenefitPlanExpectedFutureBenefitPaymentsForNextTenYears_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Estimated benefit payments for next 10 years, total</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_DefinedBenefitPlanExpectedFutureBenefitPaymentsForNextTenYears_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Benefit Plan Expected Future Benefit Payments For Next Ten Years</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Benefit Plan Weighted Average Assumptions Used In Calculating Net Periodic Benefit Cost [Abstract]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract" xlink:to="us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract_lbl" />
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Discount rate</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate" xlink:to="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Benefit Plan Assumptions Used Calculating Net Periodic Benefit Cost Discount Rate</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostRateOfCompensationIncrease" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostRateOfCompensationIncrease" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostRateOfCompensationIncrease_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Rate of increase in salary levels</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostRateOfCompensationIncrease" xlink:to="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostRateOfCompensationIncrease_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostRateOfCompensationIncrease_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Benefit Plan Assumptions Used Calculating Net Periodic Benefit Cost Rate Of Compensation Increase</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Expected long-term rate of return on assets</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets" xlink:to="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Benefit Plan Assumptions Used Calculating Net Periodic Benefit Cost Expected Long Term Return On Assets</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_DefinedBenefitPlanAssetsForPlanBenefitsPercentage" xlink:type="locator" xlink:label="mksi_DefinedBenefitPlanAssetsForPlanBenefitsPercentage" />
    <link:label xml:lang="en-US" xlink:label="mksi_DefinedBenefitPlanAssetsForPlanBenefitsPercentage_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Defined Benefit Plan Assets For Plan Benefits Percentage</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_DefinedBenefitPlanAssetsForPlanBenefitsPercentage" xlink:to="mksi_DefinedBenefitPlanAssetsForPlanBenefitsPercentage_lbl" />
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Defined Benefit Plan, Plan Assets, Category</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis" xlink:to="us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Benefit Plan By Plan Asset Categories [Axis]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PlanAssetCategoriesDomain" xlink:type="locator" xlink:label="us-gaap_PlanAssetCategoriesDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PlanAssetCategoriesDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Defined Benefit Plan, Plan Assets, Category</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PlanAssetCategoriesDomain" xlink:to="us-gaap_PlanAssetCategoriesDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PlanAssetCategoriesDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Plan Asset Categories [Domain]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanCashMember" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanCashMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanCashMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Cash [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanCashMember" xlink:to="us-gaap_DefinedBenefitPlanCashMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanCashMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Benefit Plan Cash [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanDebtSecurityMember" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanDebtSecurityMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanDebtSecurityMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Debt Securities [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanDebtSecurityMember" xlink:to="us-gaap_DefinedBenefitPlanDebtSecurityMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanDebtSecurityMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Benefit Plan Debt Security [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanEquitySecuritiesMember" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanEquitySecuritiesMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanEquitySecuritiesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Equity Securities [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanEquitySecuritiesMember" xlink:to="us-gaap_DefinedBenefitPlanEquitySecuritiesMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanEquitySecuritiesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Benefit Plan Equity Securities [Member]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_DefinedBenefitPlanAssetCategoriesOtherAssetsMember" xlink:type="locator" xlink:label="mksi_DefinedBenefitPlanAssetCategoriesOtherAssetsMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_DefinedBenefitPlanAssetCategoriesOtherAssetsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Defined benefit plan asset categories other assets.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_DefinedBenefitPlanAssetCategoriesOtherAssetsMember" xlink:to="mksi_DefinedBenefitPlanAssetCategoriesOtherAssetsMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_DefinedBenefitPlanAssetCategoriesOtherAssetsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_DefinedBenefitPlanAssetCategoriesOtherAssetsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Benefit Plan Asset Categories Other Assets [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Defined benefit plan assets, amount</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_DefinedBenefitPlanAssetsForPlanBenefitsPercentage_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Defined benefit plan assets, percentage</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_DefinedBenefitPlanAssetsForPlanBenefitsPercentage_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Benefit Plan Assets For Plan Benefits Percentage</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_DefinedBenefitPlanVestedBenefitObligation" xlink:type="locator" xlink:label="mksi_DefinedBenefitPlanVestedBenefitObligation" />
    <link:label xml:lang="en-US" xlink:label="mksi_DefinedBenefitPlanVestedBenefitObligation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Defined benefit plan vested benefit obligation.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_DefinedBenefitPlanVestedBenefitObligation" xlink:to="mksi_DefinedBenefitPlanVestedBenefitObligation_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_DefinedBenefitPlanVestedBenefitObligation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Defined benefit plan, vested benefit obligations</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_DefinedBenefitPlanVestedBenefitObligation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Benefit Plan Vested Benefit Obligation</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_DefinedBenefitPlanAssetsForPlanBenefitsGuaranteedRateOfReturn" xlink:type="locator" xlink:label="mksi_DefinedBenefitPlanAssetsForPlanBenefitsGuaranteedRateOfReturn" />
    <link:label xml:lang="en-US" xlink:label="mksi_DefinedBenefitPlanAssetsForPlanBenefitsGuaranteedRateOfReturn_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Defined benefit plan assets for plan benefits guaranteed rate of return.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_DefinedBenefitPlanAssetsForPlanBenefitsGuaranteedRateOfReturn" xlink:to="mksi_DefinedBenefitPlanAssetsForPlanBenefitsGuaranteedRateOfReturn_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_DefinedBenefitPlanAssetsForPlanBenefitsGuaranteedRateOfReturn_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Defined benefit plan assets guaranteed rate of return</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_DefinedBenefitPlanAssetsForPlanBenefitsGuaranteedRateOfReturn_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Benefit Plan Assets For Plan Benefits Guaranteed Rate Of Return</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_WeightedAverageNumberOfDilutedShares" xlink:type="locator" xlink:label="mksi_WeightedAverageNumberOfDilutedShares" />
    <link:label xml:lang="en-US" xlink:label="mksi_WeightedAverageNumberOfDilutedShares_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Weighted average number of diluted shares.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_WeightedAverageNumberOfDilutedShares" xlink:to="mksi_WeightedAverageNumberOfDilutedShares_lbl" />
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetIncomeLossAbstract" xlink:type="locator" xlink:label="us-gaap_NetIncomeLossAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_NetIncomeLossAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Numerator:</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NetIncomeLossAbstract" xlink:to="us-gaap_NetIncomeLossAbstract_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_NetIncomeLossAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Net Income Loss [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Denominator:</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Shares used in net income per common share &#8211; basic</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements" xlink:type="locator" xlink:label="us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Effect of dilutive securities</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements" xlink:to="us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Incremental Common Shares Attributable To Share Based Payment Arrangements</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_WeightedAverageNumberOfDilutedShares_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Shares used in net income per common share &#8211; diluted</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_WeightedAverageNumberOfDilutedShares_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Weighted Average Number Of Diluted Shares</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EarningsPerShareBasicAndDilutedAbstract" xlink:type="locator" xlink:label="us-gaap_EarningsPerShareBasicAndDilutedAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EarningsPerShareBasicAndDilutedAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Net income per common share:</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EarningsPerShareBasicAndDilutedAbstract" xlink:to="us-gaap_EarningsPerShareBasicAndDilutedAbstract_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EarningsPerShareBasicAndDilutedAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Earnings Per Share Basic And Diluted [Abstract]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_EarningsPerShareLineItems" xlink:type="locator" xlink:label="mksi_EarningsPerShareLineItems" />
    <link:label xml:lang="en-US" xlink:label="mksi_EarningsPerShareLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Earnings Per Share [Line Items]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_EarningsPerShareLineItems" xlink:to="mksi_EarningsPerShareLineItems_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_ScheduleOfEarningsPerShareTable" xlink:type="locator" xlink:label="mksi_ScheduleOfEarningsPerShareTable" />
    <link:label xml:lang="en-US" xlink:label="mksi_ScheduleOfEarningsPerShareTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Schedule Of Earnings Per Share [Table]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_ScheduleOfEarningsPerShareTable" xlink:to="mksi_ScheduleOfEarningsPerShareTable_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_ScheduleOfEarningsPerShareTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule Of Earnings Per Share [Table]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_ScheduleOfEarningsPerShareTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Earnings Per Share [Table]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" xlink:type="locator" xlink:label="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Antidilutive Securities</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" xlink:to="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Antidilutive Securities Excluded From Computation Of Earnings Per Share By Antidilutive Securities [Axis]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain" xlink:type="locator" xlink:label="us-gaap_AntidilutiveSecuritiesNameDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AntidilutiveSecuritiesNameDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Antidilutive Securities, Name</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AntidilutiveSecuritiesNameDomain" xlink:to="us-gaap_AntidilutiveSecuritiesNameDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AntidilutiveSecuritiesNameDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Antidilutive Securities Name [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_EarningsPerShareLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Earnings Per Share [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_EarningsPerShareLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Earnings Per Share [Line Items]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xlink:type="locator" xlink:label="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Number of shares excluded from computation of diluted earnings per share</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xlink:to="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule Of Segment Reporting Information By Segment [Table]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:to="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Segment Reporting Information By Segment [Table]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_TopTenCustomersMember" xlink:type="locator" xlink:label="mksi_TopTenCustomersMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_TopTenCustomersMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Top ten customers.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_TopTenCustomersMember" xlink:to="mksi_TopTenCustomersMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_TopTenCustomersMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Top Ten Customers [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_TopTenCustomersMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Top Ten Customers [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SegmentReportingInformationLineItems" xlink:type="locator" xlink:label="us-gaap_SegmentReportingInformationLineItems" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SegmentReportingInformationLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Segment Reporting Information [Line Items]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SegmentReportingInformationLineItems" xlink:to="us-gaap_SegmentReportingInformationLineItems_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SegmentReportingInformationLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Segment Reporting Information [Line Items]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NumberOfReportableSegments" xlink:type="locator" xlink:label="us-gaap_NumberOfReportableSegments" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_NumberOfReportableSegments_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Number of reportable segments</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NumberOfReportableSegments" xlink:to="us-gaap_NumberOfReportableSegments_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_NumberOfReportableSegments_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Number Of Reportable Segments</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_GrossProfit_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Gross profit</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_BusinessCombinationIntegrationReversalOfAcquisitionAndIntegrationCosts_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Acquisition and integration costs</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_BusinessCombinationIntegrationReversalOfAcquisitionAndIntegrationCosts_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Business Combination Integration Reversal Of Acquisition And Integration Costs</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_FeesAndExpensesRelatedToRepricingOfTermLoanFacility_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Fees and expenses related to repricing of Term Loan Facility</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_FeesAndExpensesRelatedToRepricingOfTermLoanFacility_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Fees And Expenses Related To Repricing Of Term Loan Facility</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NonoperatingIncomeExpense" xlink:type="locator" xlink:label="us-gaap_NonoperatingIncomeExpense" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_NonoperatingIncomeExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Other expense, net</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NonoperatingIncomeExpense" xlink:to="us-gaap_NonoperatingIncomeExpense_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_NonoperatingIncomeExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Nonoperating Income Expense</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Capital expenditures</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_SegmentAssets" xlink:type="locator" xlink:label="mksi_SegmentAssets" />
    <link:label xml:lang="en-US" xlink:label="mksi_SegmentAssets_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Segment assets.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_SegmentAssets" xlink:to="mksi_SegmentAssets_lbl" />
    <link:loc xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ConsolidationItemsAxis" xlink:type="locator" xlink:label="srt_ConsolidationItemsAxis" />
    <link:label xml:lang="en-US" xlink:label="srt_ConsolidationItemsAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Consolidation Items</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_ConsolidationItemsAxis" xlink:to="srt_ConsolidationItemsAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="srt_ConsolidationItemsAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Consolidation Items [Axis]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ConsolidationItemsDomain" xlink:type="locator" xlink:label="srt_ConsolidationItemsDomain" />
    <link:label xml:lang="en-US" xlink:label="srt_ConsolidationItemsDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Consolidation Items</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_ConsolidationItemsDomain" xlink:to="srt_ConsolidationItemsDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="srt_ConsolidationItemsDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Consolidation Items [Domain]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingSegmentsMember" xlink:type="locator" xlink:label="us-gaap_OperatingSegmentsMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingSegmentsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating Segments [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingSegmentsMember" xlink:to="us-gaap_OperatingSegmentsMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingSegmentsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Operating Segments [Member]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_CorporateReconcilingItemsAndEliminationsMember" xlink:type="locator" xlink:label="mksi_CorporateReconcilingItemsAndEliminationsMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_CorporateReconcilingItemsAndEliminationsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Corporate reconciling items and eliminations.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_CorporateReconcilingItemsAndEliminationsMember" xlink:to="mksi_CorporateReconcilingItemsAndEliminationsMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_CorporateReconcilingItemsAndEliminationsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Corporate, Eliminations &amp; Other [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_CorporateReconcilingItemsAndEliminationsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Corporate Reconciling Items And Eliminations [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_AccountsReceivableNetCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/positiveVerboseLabel">Accounts Receivable</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_InventoryNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Inventory</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_SegmentAssets_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total assets</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_SegmentAssets_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Segment Assets</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ReconciliationOfAssetsFromSegmentToConsolidatedTable" xlink:type="locator" xlink:label="us-gaap_ReconciliationOfAssetsFromSegmentToConsolidatedTable" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ReconciliationOfAssetsFromSegmentToConsolidatedTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Reconciliation Of Assets From Segment To Consolidated [Table]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ReconciliationOfAssetsFromSegmentToConsolidatedTable" xlink:to="us-gaap_ReconciliationOfAssetsFromSegmentToConsolidatedTable_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ReconciliationOfAssetsFromSegmentToConsolidatedTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Reconciliation Of Assets From Segment To Consolidated [Table]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_MaterialReconcilingItemsMember" xlink:type="locator" xlink:label="us-gaap_MaterialReconcilingItemsMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_MaterialReconcilingItemsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Segment Reconciling Items [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_MaterialReconcilingItemsMember" xlink:to="us-gaap_MaterialReconcilingItemsMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_MaterialReconcilingItemsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Material Reconciling Items [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SegmentReportingAssetReconcilingItemLineItems" xlink:type="locator" xlink:label="us-gaap_SegmentReportingAssetReconcilingItemLineItems" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SegmentReportingAssetReconcilingItemLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Segment Reporting, Asset Reconciling Item [Line Items]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SegmentReportingAssetReconcilingItemLineItems" xlink:to="us-gaap_SegmentReportingAssetReconcilingItemLineItems_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SegmentReportingAssetReconcilingItemLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Segment Reporting Asset Reconciling Item [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_SegmentAssets_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Total segment assets</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseRightOfUseAsset_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Right-of-use assets</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IntangibleAssetsNetIncludingGoodwill" xlink:type="locator" xlink:label="us-gaap_IntangibleAssetsNetIncludingGoodwill" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IntangibleAssetsNetIncludingGoodwill_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Goodwill and intangible assets, net</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IntangibleAssetsNetIncludingGoodwill" xlink:to="us-gaap_IntangibleAssetsNetIncludingGoodwill_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IntangibleAssetsNetIncludingGoodwill_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Intangible Assets Net Including Goodwill</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_OtherAssetsNoncurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Other assets and long-term assets</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_Assets_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Consolidated total assets</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule Of Revenues From External Customers And Long Lived Assets [Table]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable" xlink:to="us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Revenues From External Customers And Long Lived Assets [Table]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_NorthAmericaMember" xlink:type="locator" xlink:label="srt_NorthAmericaMember" />
    <link:label xml:lang="en-US" xlink:label="srt_NorthAmericaMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">North America [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_NorthAmericaMember" xlink:to="srt_NorthAmericaMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="srt_NorthAmericaMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">North America [Member]</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/country/2021/country-2021.xsd#country_KR" xlink:type="locator" xlink:label="country_KR" />
    <link:label xml:lang="en-US" xlink:label="country_KR_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">South Korea [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="country_KR" xlink:to="country_KR_lbl" />
    <link:label xml:lang="en-US" xlink:label="country_KR_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">KOREA, REPUBLIC OF</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/country/2021/country-2021.xsd#country_CN" xlink:type="locator" xlink:label="country_CN" />
    <link:label xml:lang="en-US" xlink:label="country_CN_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">China [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="country_CN" xlink:to="country_CN_lbl" />
    <link:label xml:lang="en-US" xlink:label="country_CN_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">CHINA</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/country/2021/country-2021.xsd#country_TW" xlink:type="locator" xlink:label="country_TW" />
    <link:label xml:lang="en-US" xlink:label="country_TW_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Taiwan [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="country_TW" xlink:to="country_TW_lbl" />
    <link:label xml:lang="en-US" xlink:label="country_TW_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">TAIWAN, PROVINCE OF CHINA</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_OtherAsiaMember" xlink:type="locator" xlink:label="mksi_OtherAsiaMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_OtherAsiaMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Other Asia.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_OtherAsiaMember" xlink:to="mksi_OtherAsiaMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_OtherAsiaMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other Asia [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_OtherAsiaMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Other Asia [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_EuropeMember" xlink:type="locator" xlink:label="srt_EuropeMember" />
    <link:label xml:lang="en-US" xlink:label="srt_EuropeMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Europe [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_EuropeMember" xlink:to="srt_EuropeMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="srt_EuropeMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Europe [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_AsiaMember" xlink:type="locator" xlink:label="srt_AsiaMember" />
    <link:label xml:lang="en-US" xlink:label="srt_AsiaMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Asia [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_AsiaMember" xlink:to="srt_AsiaMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="srt_AsiaMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Asia [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems" xlink:type="locator" xlink:label="us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Revenues from External Customers and Long-Lived Assets [Line Items]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems" xlink:to="us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Revenues From External Customers And Long Lived Assets [Line Items]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NoncurrentAssets" xlink:type="locator" xlink:label="us-gaap_NoncurrentAssets" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_NoncurrentAssets_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Long-lived assets</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NoncurrentAssets" xlink:to="us-gaap_NoncurrentAssets_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_NoncurrentAssets_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Noncurrent Assets</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_NumberOfCustomersAccountedForFortySevenPercentFortyFourPercentAndThirtyThreePercentOfRevenue" xlink:type="locator" xlink:label="mksi_NumberOfCustomersAccountedForFortySevenPercentFortyFourPercentAndThirtyThreePercentOfRevenue" />
    <link:label xml:lang="en-US" xlink:label="mksi_NumberOfCustomersAccountedForFortySevenPercentFortyFourPercentAndThirtyThreePercentOfRevenue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Number of customers accounted for forty seven percent forty four percent and thirty three percent of revenue.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_NumberOfCustomersAccountedForFortySevenPercentFortyFourPercentAndThirtyThreePercentOfRevenue" xlink:to="mksi_NumberOfCustomersAccountedForFortySevenPercentFortyFourPercentAndThirtyThreePercentOfRevenue_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_NumberOfCustomersAccountedForNinetyPercentOfRevenue" xlink:type="locator" xlink:label="mksi_NumberOfCustomersAccountedForNinetyPercentOfRevenue" />
    <link:label xml:lang="en-US" xlink:label="mksi_NumberOfCustomersAccountedForNinetyPercentOfRevenue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Number of customers accounted for ninety percent of revenue</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_NumberOfCustomersAccountedForNinetyPercentOfRevenue" xlink:to="mksi_NumberOfCustomersAccountedForNinetyPercentOfRevenue_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_NumberOfCustomersAccountedForTenOrMorePercentOfRevenue" xlink:type="locator" xlink:label="mksi_NumberOfCustomersAccountedForTenOrMorePercentOfRevenue" />
    <link:label xml:lang="en-US" xlink:label="mksi_NumberOfCustomersAccountedForTenOrMorePercentOfRevenue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Number of customers accounted for ten or more percent of revenue.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_NumberOfCustomersAccountedForTenOrMorePercentOfRevenue" xlink:to="mksi_NumberOfCustomersAccountedForTenOrMorePercentOfRevenue_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_NumberOfCustomersAccountedForFortySevenPercentFortyFourPercentAndThirtyThreePercentOfRevenue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Number of customers accounted for 47% ,44% and 33% of net revenue</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_NumberOfCustomersAccountedForFortySevenPercentFortyFourPercentAndThirtyThreePercentOfRevenue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Number Of Customers Accounted For Forty Seven Percent Forty Four Percent And Thirty Three Percent Of Revenue</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_NumberOfCustomersAccountedForNinetyPercentOfRevenue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Number of customers accounted for greater than 90 % of net revenue</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_NumberOfCustomersAccountedForNinetyPercentOfRevenue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Number Of Customers Accounted For Ninety Percent Of Revenue</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_NumberOfCustomersAccountedForTenOrMorePercentOfRevenue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Number of customers accounted for 10% or more of total revenue</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_NumberOfCustomersAccountedForTenOrMorePercentOfRevenue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Number Of Customers Accounted For Ten Or More Percent Of Revenue</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_CustomerOneMember" xlink:type="locator" xlink:label="mksi_CustomerOneMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_CustomerOneMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Customer one.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_CustomerOneMember" xlink:to="mksi_CustomerOneMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_CustomerOneMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Lam Research Corporation [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_CustomerOneMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Customer One [Member]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_CustomerTwoMember" xlink:type="locator" xlink:label="mksi_CustomerTwoMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_CustomerTwoMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Customer two.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_CustomerTwoMember" xlink:to="mksi_CustomerTwoMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_CustomerTwoMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Applied Materials, Inc. [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_CustomerTwoMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Customer Two [Member]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_NumberOfFacilitiesYetToClose" xlink:type="locator" xlink:label="mksi_NumberOfFacilitiesYetToClose" />
    <link:label xml:lang="en-US" xlink:label="mksi_NumberOfFacilitiesYetToClose_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Number of facilities yet to close.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_NumberOfFacilitiesYetToClose" xlink:to="mksi_NumberOfFacilitiesYetToClose_lbl" />
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RestructuringAndRelatedActivitiesAbstract" xlink:type="locator" xlink:label="us-gaap_RestructuringAndRelatedActivitiesAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RestructuringAndRelatedActivitiesAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Restructuring And Related Activities [Abstract]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RestructuringAndRelatedActivitiesAbstract" xlink:to="us-gaap_RestructuringAndRelatedActivitiesAbstract_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_RestructuringCostAndOtherCostLineItems" xlink:type="locator" xlink:label="mksi_RestructuringCostAndOtherCostLineItems" />
    <link:label xml:lang="en-US" xlink:label="mksi_RestructuringCostAndOtherCostLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Restructuring cost and other cost.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_RestructuringCostAndOtherCostLineItems" xlink:to="mksi_RestructuringCostAndOtherCostLineItems_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_ScheduleOfRestructuringAndOtherCostTable" xlink:type="locator" xlink:label="mksi_ScheduleOfRestructuringAndOtherCostTable" />
    <link:label xml:lang="en-US" xlink:label="mksi_ScheduleOfRestructuringAndOtherCostTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Schedule of restructuring and other cost.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_ScheduleOfRestructuringAndOtherCostTable" xlink:to="mksi_ScheduleOfRestructuringAndOtherCostTable_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_ScheduleOfRestructuringAndOtherCostTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule Of Restructuring And Other Cost [Table]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_ScheduleOfRestructuringAndOtherCostTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Restructuring And Other Cost [Table]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_RestructuringCostAndOtherCostLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Restructuring Cost and Other Cost [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_RestructuringCostAndOtherCostLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Restructuring Cost And Other Cost [Line Items]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RestructuringCharges" xlink:type="locator" xlink:label="us-gaap_RestructuringCharges" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RestructuringCharges_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Restructuring charges</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RestructuringCharges" xlink:to="us-gaap_RestructuringCharges_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RestructuringCharges_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Restructuring Charges</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_NumberOfFacilitiesYetToClose_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Number of facilities yet to close</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_NumberOfFacilitiesYetToClose_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Number Of Facilities Yet To Close</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_PaymentsAndAdjustmentForRestructuring" xlink:type="locator" xlink:label="mksi_PaymentsAndAdjustmentForRestructuring" />
    <link:label xml:lang="en-US" xlink:label="mksi_PaymentsAndAdjustmentForRestructuring_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Payments and adjustment for restructuring.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_PaymentsAndAdjustmentForRestructuring" xlink:to="mksi_PaymentsAndAdjustmentForRestructuring_lbl" />
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RestructuringReserve" xlink:type="locator" xlink:label="us-gaap_RestructuringReserve" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RestructuringReserve_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Balance at January 1</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RestructuringReserve" xlink:to="us-gaap_RestructuringReserve_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RestructuringReserve_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Restructuring Reserve</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_PaymentsAndAdjustmentForRestructuring_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Payments and adjustments</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_PaymentsAndAdjustmentForRestructuring_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Payments And Adjustment For Restructuring</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_RestructuringReserve_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Balance at December 31</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_InsuranceReimbursementReceived" xlink:type="locator" xlink:label="mksi_InsuranceReimbursementReceived" />
    <link:label xml:lang="en-US" xlink:label="mksi_InsuranceReimbursementReceived_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Insurance reimbursement received.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_InsuranceReimbursementReceived" xlink:to="mksi_InsuranceReimbursementReceived_lbl" />
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherRestructuringCosts" xlink:type="locator" xlink:label="us-gaap_OtherRestructuringCosts" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OtherRestructuringCosts_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other restructuring charges, facility cost</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherRestructuringCosts" xlink:to="us-gaap_OtherRestructuringCosts_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OtherRestructuringCosts_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Other Restructuring Costs</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_InsuranceReimbursementReceived_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Insurance reimbursement received</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_InsuranceReimbursementReceived_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Insurance Reimbursement Received</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_CommitmentsAndContingenciesLineItems" xlink:type="locator" xlink:label="mksi_CommitmentsAndContingenciesLineItems" />
    <link:label xml:lang="en-US" xlink:label="mksi_CommitmentsAndContingenciesLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Commitments and contingencies.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_CommitmentsAndContingenciesLineItems" xlink:to="mksi_CommitmentsAndContingenciesLineItems_lbl" />
    <link:loc xlink:href="mksi-20211231.xsd#mksi_CommitmentsAndContingenciesTable" xlink:type="locator" xlink:label="mksi_CommitmentsAndContingenciesTable" />
    <link:label xml:lang="en-US" xlink:label="mksi_CommitmentsAndContingenciesTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Commitments and contingencies.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_CommitmentsAndContingenciesTable" xlink:to="mksi_CommitmentsAndContingenciesTable_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_CommitmentsAndContingenciesTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Commitments And Contingencies [Table]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_CommitmentsAndContingenciesTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Commitments And Contingencies [Table]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_NewTermLoanFacilityMember" xlink:type="locator" xlink:label="mksi_NewTermLoanFacilityMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_NewTermLoanFacilityMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">New term loan facility.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_NewTermLoanFacilityMember" xlink:to="mksi_NewTermLoanFacilityMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_NewTermLoanFacilityMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">New Term Loan Facility [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_NewTermLoanFacilityMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">New Term Loan Facility [Member]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_USDollarTrancheMember" xlink:type="locator" xlink:label="mksi_USDollarTrancheMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_USDollarTrancheMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">US Dollar tranche.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_USDollarTrancheMember" xlink:to="mksi_USDollarTrancheMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_USDollarTrancheMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">U.S. Dollar Tranche [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_USDollarTrancheMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">U S Dollar Tranche [Member]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_EuroTrancheMember" xlink:type="locator" xlink:label="mksi_EuroTrancheMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_EuroTrancheMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Euro tranche.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_EuroTrancheMember" xlink:to="mksi_EuroTrancheMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_EuroTrancheMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Euro Tranche</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_EuroTrancheMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Euro Tranche [Member]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_OriginalIssueDiscountMember" xlink:type="locator" xlink:label="mksi_OriginalIssueDiscountMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_OriginalIssueDiscountMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Original issue discount.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_OriginalIssueDiscountMember" xlink:to="mksi_OriginalIssueDiscountMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_OriginalIssueDiscountMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Original Issue Discount</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_OriginalIssueDiscountMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Original Issue Discount [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_CommitmentsAndContingenciesLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Commitments And Contingencies [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_CommitmentsAndContingenciesLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Commitments And Contingencies [Line Items]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessAcquisitionDateOfAcquisitionAgreement1" xlink:type="locator" xlink:label="us-gaap_BusinessAcquisitionDateOfAcquisitionAgreement1" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_BusinessAcquisitionDateOfAcquisitionAgreement1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Date of acquisition agreement</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BusinessAcquisitionDateOfAcquisitionAgreement1" xlink:to="us-gaap_BusinessAcquisitionDateOfAcquisitionAgreement1_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_BusinessAcquisitionDateOfAcquisitionAgreement1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Business Acquisition Date Of Acquisition Agreement1</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PaymentsToAcquireBusinessesGross" xlink:type="locator" xlink:label="us-gaap_PaymentsToAcquireBusinessesGross" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PaymentsToAcquireBusinessesGross_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Business acquisition, total value of aggregate cash and stock consideration</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PaymentsToAcquireBusinessesGross" xlink:to="us-gaap_PaymentsToAcquireBusinessesGross_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PaymentsToAcquireBusinessesGross_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Payments To Acquire Businesses Gross</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentFaceAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Senior secured credit facility</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_SignificantSupplyCommitmentTimePeriod" xlink:type="locator" xlink:label="mksi_SignificantSupplyCommitmentTimePeriod" />
    <link:label xml:lang="en-US" xlink:label="mksi_SignificantSupplyCommitmentTimePeriod_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Majority of MKS purchase commitment arrangement time period/term.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_SignificantSupplyCommitmentTimePeriod" xlink:to="mksi_SignificantSupplyCommitmentTimePeriod_lbl" />
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PurchaseCommitmentRemainingMinimumAmountCommitted" xlink:type="locator" xlink:label="us-gaap_PurchaseCommitmentRemainingMinimumAmountCommitted" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PurchaseCommitmentRemainingMinimumAmountCommitted_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Purchase commitments covered by aggregate value</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PurchaseCommitmentRemainingMinimumAmountCommitted" xlink:to="us-gaap_PurchaseCommitmentRemainingMinimumAmountCommitted_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PurchaseCommitmentRemainingMinimumAmountCommitted_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Purchase Commitment Remaining Minimum Amount Committed</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_SignificantSupplyCommitmentTimePeriod_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Purchase commitments</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_SignificantSupplyCommitmentTimePeriod_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Significant Supply Commitment Time Period</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PurchaseObligation" xlink:type="locator" xlink:label="us-gaap_PurchaseObligation" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PurchaseObligation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Liabilities. purchase obligation</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_PurchaseObligation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Purchase Obligation</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ValuationAndQualifyingAccountsDisclosureTable" xlink:type="locator" xlink:label="srt_ValuationAndQualifyingAccountsDisclosureTable" />
    <link:label xml:lang="en-US" xlink:label="srt_ValuationAndQualifyingAccountsDisclosureTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Valuation And Qualifying Accounts Disclosure [Table]</link:label>
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    <link:label xml:lang="en-US" xlink:label="srt_ValuationAndQualifyingAccountsDisclosureTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Valuation And Qualifying Accounts Disclosure [Table]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ValuationAllowancesAndReservesTypeAxis" xlink:type="locator" xlink:label="us-gaap_ValuationAllowancesAndReservesTypeAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ValuationAllowancesAndReservesTypeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">SEC Schedule, 12-09, Valuation Allowances and Reserves Type</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ValuationAllowancesAndReservesTypeAxis" xlink:to="us-gaap_ValuationAllowancesAndReservesTypeAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ValuationAllowancesAndReservesTypeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Valuation Allowances And Reserves Type [Axis]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ValuationAllowancesAndReservesDomain" xlink:type="locator" xlink:label="us-gaap_ValuationAllowancesAndReservesDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ValuationAllowancesAndReservesDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">SEC Schedule, 12-09, Valuation Allowances and Reserves</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ValuationAllowancesAndReservesDomain" xlink:to="us-gaap_ValuationAllowancesAndReservesDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ValuationAllowancesAndReservesDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Valuation Allowances And Reserves [Domain]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AllowanceForCreditLossMember" xlink:type="locator" xlink:label="us-gaap_AllowanceForCreditLossMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AllowanceForCreditLossMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Valuation Allowance for Doubtful Accounts [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AllowanceForCreditLossMember" xlink:to="us-gaap_AllowanceForCreditLossMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AllowanceForCreditLossMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Allowance For Credit Loss [Member]</link:label>
    <link:loc xlink:href="mksi-20211231.xsd#mksi_AllowanceForSalesReturnMember" xlink:type="locator" xlink:label="mksi_AllowanceForSalesReturnMember" />
    <link:label xml:lang="en-US" xlink:label="mksi_AllowanceForSalesReturnMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Allowance for sales return.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="mksi_AllowanceForSalesReturnMember" xlink:to="mksi_AllowanceForSalesReturnMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="mksi_AllowanceForSalesReturnMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Valuation Allowance for Sales Returns [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="mksi_AllowanceForSalesReturnMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Allowance For Sales Return [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember" xlink:type="locator" xlink:label="us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Valuation Allowance on Deferred Tax Asset [Member]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember" xlink:to="us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Valuation Allowance Of Deferred Tax Assets [Member]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ValuationAndQualifyingAccountsDisclosureLineItems" xlink:type="locator" xlink:label="srt_ValuationAndQualifyingAccountsDisclosureLineItems" />
    <link:label xml:lang="en-US" xlink:label="srt_ValuationAndQualifyingAccountsDisclosureLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Valuation and Qualifying Accounts Disclosure [Line Items]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_ValuationAndQualifyingAccountsDisclosureLineItems" xlink:to="srt_ValuationAndQualifyingAccountsDisclosureLineItems_lbl" />
    <link:label xml:lang="en-US" xlink:label="srt_ValuationAndQualifyingAccountsDisclosureLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Valuation And Qualifying Accounts Disclosure [Line Items]</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ValuationAllowancesAndReservesBalance" xlink:type="locator" xlink:label="us-gaap_ValuationAllowancesAndReservesBalance" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ValuationAllowancesAndReservesBalance_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Balance at Beginning of Year</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ValuationAllowancesAndReservesBalance" xlink:to="us-gaap_ValuationAllowancesAndReservesBalance_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ValuationAllowancesAndReservesBalance_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Valuation Allowances And Reserves Balance</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ValuationAllowancesAndReservesReservesOfBusinessesAcquired" xlink:type="locator" xlink:label="us-gaap_ValuationAllowancesAndReservesReservesOfBusinessesAcquired" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ValuationAllowancesAndReservesReservesOfBusinessesAcquired_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Additions Acquisition Beginning Balance</link:label>
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    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense" xlink:type="locator" xlink:label="us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Additions Charged to Costs and Expenses</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Valuation Allowances And Reserves Charged To Cost And Expense</link:label>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ValuationAllowancesAndReservesChargedToOtherAccounts" xlink:type="locator" xlink:label="us-gaap_ValuationAllowancesAndReservesChargedToOtherAccounts" />
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