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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2021-05-14</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001109448</issuerCik>
        <issuerName>ALLIANCEBERNSTEIN L.P.</issuerName>
        <issuerTradingSymbol>NONE</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001333986</rptOwnerCik>
            <rptOwnerName>Equitable Holdings, Inc.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1290 AVENUE OF THE AMERICAS</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10104</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Units</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <transactionDate>
                <value>2021-05-14</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F2"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>2587472</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>170121745</value>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F3"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Units representing assignments of beneficial ownership of limited partnership interests (&quot;AB Capital Units&quot;) in AllianceBernstein L.P.</footnote>
        <footnote id="F2">On May 14, 2021, Equitable Financial Life Insurance Company of America distributed 2,587,472 AB Capital Units to its sole shareholder, Equitable Financial Services, LLC. Upon receipt of the 2,587,472 AB Capital Units, Equitable Financial Services, LLC distributed these AB Capital Units to its sole member, Equitable Holdings, Inc.</footnote>
        <footnote id="F3">Equitable Holdings, Inc. beneficially owns directly 53,780,230 AB Capital Units and beneficially owns indirectly 74,406,933 AB Capital Units beneficially owned directly by Alpha Units Holdings, Inc. and 41,934,582 AB Capital Units beneficially owned directly by Alpha Units Holding II, Inc. Alpha Units Holdings, Inc and Alpha Units Holding II, Inc. are each wholly-owned subsidiaries of Equitable Holdings, Inc.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Ralph Petruzzo, Vice President and Associate General Counsel</signatureName>
        <signatureDate>2021-05-14</signatureDate>
    </ownerSignature>
</ownershipDocument>
