<SEC-DOCUMENT>0000898173-18-000118.txt : 20180510
<SEC-HEADER>0000898173-18-000118.hdr.sgml : 20180510
<ACCEPTANCE-DATETIME>20180510163123
ACCESSION NUMBER:		0000898173-18-000118
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20180509
FILED AS OF DATE:		20180510
DATE AS OF CHANGE:		20180510

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			BURCHFIELD JAY D
		CENTRAL INDEX KEY:			0001064402

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-21318
		FILM NUMBER:		18823019

	MAIL ADDRESS:	
		STREET 1:		233 S PATTERSON AVE
		CITY:			SPRINGFIELD
		STATE:			MO
		ZIP:			65802

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			O REILLY AUTOMOTIVE INC
		CENTRAL INDEX KEY:			0000898173
		STANDARD INDUSTRIAL CLASSIFICATION:	RETAIL-AUTO & HOME SUPPLY STORES [5531]
		IRS NUMBER:				274358837
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		233 S PATTERSON AVE
		CITY:			SPRINGFIELD
		STATE:			MO
		ZIP:			65802
		BUSINESS PHONE:		417-829-5878

	MAIL ADDRESS:	
		STREET 1:		233 S PATTERSON AVE
		CITY:			SPRINGFIELD
		STATE:			MO
		ZIP:			65802
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_152598426814445.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2018-05-09</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000898173</issuerCik>
        <issuerName>O REILLY AUTOMOTIVE INC</issuerName>
        <issuerTradingSymbol>ORLY</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001064402</rptOwnerCik>
            <rptOwnerName>BURCHFIELD JAY D</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>233 S. PATTERSON AVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SPRINGFIELD</rptOwnerCity>
            <rptOwnerState>MO</rptOwnerState>
            <rptOwnerZipCode>65802</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2018-05-09</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>509</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>265.41</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>19081</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Represents unvested restricted shares awarded under the Amended and Restated O'Reilly Automotive, Inc. 2003 Director's Stock Plan, which vest in three equal annual installments on May 9, 2019, 2020 and 2021.</footnote>
        <footnote id="F2">Total includes 1,014 unvested restricted shares awarded under the Amended and Restated O'Reilly Automotive, Inc. 2003 Director's Stock Plan and 18,067 shares held directly by Mr. Burchfield.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Jay D. Burchfield</signatureName>
        <signatureDate>2018-05-10</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
