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

    <schemaVersion>X0407</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2023-04-25</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001333822</issuerCik>
        <issuerName>SemiLEDs Corp</issuerName>
        <issuerTradingSymbol>LEDS</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001630738</rptOwnerCik>
            <rptOwnerName>Lee Hsin-Liang Christopher</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>3F, NO. 11 KE JUNG RD., CHU-NAN SITE</rptOwnerStreet1>
            <rptOwnerStreet2>HSINCHU SCIENCE PARK, MIAO LI COUNTY</rptOwnerStreet2>
            <rptOwnerCity>CHU-NAN</rptOwnerCity>
            <rptOwnerState>F5</rptOwnerState>
            <rptOwnerZipCode>F5 350</rptOwnerZipCode>
            <rptOwnerStateDescription>TAIWAN</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chief Financial Officer</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2023-04-25</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>8000</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>25800</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">These shares represent restricted stock units and will be settled in LEDS common stock upon vesting, 12.5% of the restricted stock units will vest every three months starting from the vesting commencement date of April 25, 2023, so long as the Reporting Person's continuous service through the applicable vesting date. These restricted stock units will become fully vested upon a change of control.</footnote>
        <footnote id="F2">Reflects one-for-ten reverse stock split on April 15th, 2016.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/Christopher Lee</signatureName>
        <signatureDate>2023-04-26</signatureDate>
    </ownerSignature>
</ownershipDocument>
