<SEC-DOCUMENT>0001628280-19-003611.txt : 20190328
<SEC-HEADER>0001628280-19-003611.hdr.sgml : 20190328
<ACCEPTANCE-DATETIME>20190328191028
ACCESSION NUMBER:		0001628280-19-003611
CONFORMED SUBMISSION TYPE:	3
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20190322
FILED AS OF DATE:		20190328
DATE AS OF CHANGE:		20190328

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Steimberg Amichai
		CENTRAL INDEX KEY:			0001771362

	FILING VALUES:
		FORM TYPE:		3
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-09992
		FILM NUMBER:		19713441

	MAIL ADDRESS:	
		STREET 1:		ONE TECHNOLOGY DRIVE
		CITY:			MILPITAS
		STATE:			CA
		ZIP:			95035

	FORMER NAME:	
		FORMER CONFORMED NAME:	Steimberg Amichai Cannon
		DATE OF NAME CHANGE:	20190320

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			KLA TENCOR CORP
		CENTRAL INDEX KEY:			0000319201
		STANDARD INDUSTRIAL CLASSIFICATION:	OPTICAL INSTRUMENTS & LENSES [3827]
		IRS NUMBER:				042564110
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0630

	BUSINESS ADDRESS:	
		STREET 1:		ONE TECHNOLOGY DRIVE
		CITY:			MILPITAS
		STATE:			CA
		ZIP:			95035
		BUSINESS PHONE:		4088756000

	MAIL ADDRESS:	
		STREET 1:		ONE TECHNOLOGY DRIVE
		CITY:			MILPITAS
		STATE:			CA
		ZIP:			95035

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	KLA INSTRUMENTS CORP
		DATE OF NAME CHANGE:	19920703
</SEC-HEADER>
<DOCUMENT>
<TYPE>3
<SEQUENCE>1
<FILENAME>wf-form3_155381461247541.xml
<DESCRIPTION>FORM 3
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0206</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2019-03-22</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0000319201</issuerCik>
        <issuerName>KLA TENCOR CORP</issuerName>
        <issuerTradingSymbol>KLAC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001771362</rptOwnerCik>
            <rptOwnerName>Steimberg Amichai</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>ONE TECHNOLOGY DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>MILPITAS</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>95035</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>CEO - Orbotech Ltd.</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>18292</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock - Restricted Stock Units</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>34470</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Each restricted stock unit (&quot;RSU&quot;) represents a contingent right to receive one share of KLA-Tencor common stock. Does not include performance-based RSUs, if any, held by the Reporting Person for which an assessment has not yet been made regarding the achievement of the applicable performance goals. Any such holdings will be reported on a Form 4 within two business days of the date such assessment is made.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Jeffrey Cannon, attorney-in-fact</signatureName>
        <signatureDate>2019-03-28</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
