<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

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

    <issuer>
        <issuerCik>0001616817</issuerCik>
        <issuerName>Metaldyne Performance Group Inc.</issuerName>
        <issuerTradingSymbol>MPG</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001625944</rptOwnerCik>
            <rptOwnerName>Blaufuss Mark</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O METALDYNE PERFORMANCE GROUP INC.</rptOwnerStreet1>
            <rptOwnerStreet2>ONE TOWNE SQUARE, SUITE 550</rptOwnerStreet2>
            <rptOwnerCity>SOUTHFIELD</rptOwnerCity>
            <rptOwnerState>MI</rptOwnerState>
            <rptOwnerZipCode>48076</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isOfficer>1</isOfficer>
            <officerTitle>Chief Financial Officer</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, Par Value $0.001 Per Share</value>
            </securityTitle>
            <transactionDate>
                <value>2016-09-01</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>16963</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>15.84</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>254287</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes></footnotes>

    <remarks>29,969 shares vested (33.3% of the award) and 16,963 shares were withheld for tax liability required at the time of vesting.</remarks>

    <ownerSignature>
        <signatureName>Mark Blaufuss</signatureName>
        <signatureDate>2016-09-06</signatureDate>
    </ownerSignature>
</ownershipDocument>
