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

    <schemaVersion>X0508</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2023-11-10</periodOfReport>

    <notSubjectToSection16>true</notSubjectToSection16>

    <issuer>
        <issuerCik>0001948368</issuerCik>
        <issuerName>Phillip Street Middle Market Lending Fund LLC</issuerName>
        <issuerTradingSymbol>NONE</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001806913</rptOwnerCik>
            <rptOwnerName>Pessah David</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>200 WEST STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10282</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isOfficer>true</isOfficer>
            <officerTitle>See Remarks</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>false</aff10b5One>

    <remarks>Effective at the close of business on November 10, 2023, the reporting person no longer serves as Chief Financial Officer, Treasurer and Principal Accounting Officer of Phillip Street Middle Market Lending Fund LLC.</remarks>

    <ownerSignature>
        <signatureName>/s/ Edward Meehan, Attorney-in-fact</signatureName>
        <signatureDate>2023-11-16</signatureDate>
    </ownerSignature>
</ownershipDocument>
