<SEC-DOCUMENT>0001209191-16-140297.txt : 20160906
<SEC-HEADER>0001209191-16-140297.hdr.sgml : 20160906
<ACCEPTANCE-DATETIME>20160906195804
ACCESSION NUMBER:		0001209191-16-140297
CONFORMED SUBMISSION TYPE:	3
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20160901
FILED AS OF DATE:		20160906
DATE AS OF CHANGE:		20160906

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			MPLX LP
		CENTRAL INDEX KEY:			0001552000
		STANDARD INDUSTRIAL CLASSIFICATION:	PIPE LINES (NO NATURAL GAS) [4610]
		IRS NUMBER:				270005456
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		200 E. HARDIN STREET
		CITY:			FINDLAY
		STATE:			OH
		ZIP:			45840
		BUSINESS PHONE:		(419) 421-2159

	MAIL ADDRESS:	
		STREET 1:		200 E. HARDIN STREET
		CITY:			FINDLAY
		STATE:			OH
		ZIP:			45840

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			MPLX Holdings Inc.
		CENTRAL INDEX KEY:			0001683291
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		3
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-35714
		FILM NUMBER:		161871979

	BUSINESS ADDRESS:	
		STREET 1:		539 SOUTH MAIN STREET
		CITY:			FINDLAY
		STATE:			OH
		ZIP:			45840
		BUSINESS PHONE:		419-421-2414

	MAIL ADDRESS:	
		STREET 1:		539 SOUTH MAIN STREET
		CITY:			FINDLAY
		STATE:			OH
		ZIP:			45840
</SEC-HEADER>
<DOCUMENT>
<TYPE>3
<SEQUENCE>1
<FILENAME>doc3.xml
<DESCRIPTION>FORM 3 SUBMISSION
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0206</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2016-09-01</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001552000</issuerCik>
        <issuerName>MPLX LP</issuerName>
        <issuerTradingSymbol>MPLX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001683291</rptOwnerCik>
            <rptOwnerName>MPLX Holdings Inc.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>539 S. MAIN ST.</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>FINDLAY</rptOwnerCity>
            <rptOwnerState>OH</rptOwnerState>
            <rptOwnerZipCode>45840</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Class A Units</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>28554313</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnotes</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Units (Limited Partner Interests)</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>79466136</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F3"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnotes</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Pursuant to a Master Reorganization Agreement effective September 1, 2016 by and among MPLX Holdings Inc. (&quot;Holdings&quot;), MarkWest Energy Partners, L.P., MWE GP LLC, MPLX LP (&quot;MPLX&quot;), MPLX GP LLC (&quot;the &quot;General Partner&quot;), MPC Investment LLC (&quot;MPC Investment&quot;), MPLX Logistics Holdings LLC (&quot;Logistics Holdings&quot;) and MarkWest Hydrocarbon, L.L.C. (&quot;Hydrocarbon&quot;), Holdings became a part of a reporting group which includes Marathon Petroleum Corporation (&quot;MPC&quot;), MPC Investment, the General Partner, Hydrocarbon and Logistics Holdings. MPC Investment, a direct wholly-owned subsidiary of MPC, owns all of the membership interests or stock in the General Partner, Logistics Holdings and Holdings. Holdings owned all of the membership interests in Hydrocarbon as of September 1, 2016. Accordingly, the General Partner, Logistics Holdings, Holdings and Hydrocarbon were all indirect wholly-owned subsidiaries of MPC as of the September 1, 2016.</footnote>
        <footnote id="F2">Hydrocarbon, a wholly-owned subsidiary of Holdings, owned all of the Issuer's Class A units as of September 1, 2016.</footnote>
        <footnote id="F3">As of September 1, 2016, the General Partner directly owned 7,630,225 general partner units, representing its 2% general partner interest in the Issuer and Logistics Holdings beneficially owned 79,466,136 common units representing limited partnership interests in the Issuer. MPC Investment owns all of the membership interests in Logistics Holdings and the General Partner, and MPC owns all of the membership interest in MPC Investment.  Accordingly, MPC, MPC Investment and Holdings may be deemed to have indirectly beneficially owned the securities directly held by the General Partner, Logistics Holdings and Hydrocarbon but disclaim beneficial ownership except to the extent of their respective pecuniary interests therein.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Molly R. Benson,  Director and Secretary, MPLX Holdings Inc.</signatureName>
        <signatureDate>2016-09-06</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
