<SEC-DOCUMENT>0000707549-19-000020.txt : 20190213
<SEC-HEADER>0000707549-19-000020.hdr.sgml : 20190213
<ACCEPTANCE-DATETIME>20190213191216
ACCESSION NUMBER:		0000707549-19-000020
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20190211
FILED AS OF DATE:		20190213
DATE AS OF CHANGE:		20190213

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			LORD PATRICK J
		CENTRAL INDEX KEY:			0001343531

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-12933
		FILM NUMBER:		19599844

	MAIL ADDRESS:	
		STREET 1:		C/O LAM RESEARCH CORP
		STREET 2:		4650 CUSHING PARKWAY
		CITY:			FREMONT
		STATE:			CA
		ZIP:			94538

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			LAM RESEARCH CORP
		CENTRAL INDEX KEY:			0000707549
		STANDARD INDUSTRIAL CLASSIFICATION:	SPECIAL INDUSTRY MACHINERY, NEC [3559]
		IRS NUMBER:				942634797
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0625

	BUSINESS ADDRESS:	
		STREET 1:		4650 CUSHING BLVD
		CITY:			FREMONT
		STATE:			CA
		ZIP:			94538
		BUSINESS PHONE:		5106590200

	MAIL ADDRESS:	
		STREET 1:		4650 CUSHING PARKWAY
		CITY:			FREMONT
		STATE:			CA
		ZIP:			94538
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_155010312166133.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2019-02-11</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000707549</issuerCik>
        <issuerName>LAM RESEARCH CORP</issuerName>
        <issuerTradingSymbol>LRCX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001343531</rptOwnerCik>
            <rptOwnerName>LORD PATRICK J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O LAM RESEARCH CORPORATION</rptOwnerStreet1>
            <rptOwnerStreet2>4650 CUSHING PARKWAY</rptOwnerStreet2>
            <rptOwnerCity>FREMONT</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94538</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Senior Vice President</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2019-02-11</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>8826</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>18710</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Market-based Performance Restricted Stock Unit</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0.0</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2019-02-11</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>7957</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F3"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>7957.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">On 03/01/2016, the Reporting Person received a target grant of 7,957 Market-based Performance Restricted Stock Units vesting between 0% and 150% on 03/01/2019. The performance of this award was based on the Lam Research Total Shareholder Return performance relative to the Philadelphia Semiconductor Sector Index Total Shareholder Return during the performance period of 02/01/2016 to 01/31/2019. The performance payout was approved at 110.93% of target.</footnote>
        <footnote id="F2">Amount reported includes shares subject to unvested Restricted Stock Units.</footnote>
        <footnote id="F3">These Market-based Performance Restricted Stock Units vest between 0% and 150% on 03/01/2019. The performance of this award is based on the Lam Research Total Shareholder Return performance relative to the Philadelphia Semiconductor Sector Index Total Shareholder Return during the performance period of 02/01/2016 to 01/31/2019.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Leign Cramer by Power of Attorney</signatureName>
        <signatureDate>2019-02-13</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
