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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2017-03-13</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001095996</issuerCik>
        <issuerName>WILLIAM LYON HOMES</issuerName>
        <issuerTradingSymbol>WLH</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001106191</rptOwnerCik>
            <rptOwnerName>GMT CAPITAL CORP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>GMT CAPITAL CORP</rptOwnerStreet1>
            <rptOwnerStreet2>2300 WINDY RIDGE PARKWAY SUITE 550 SOUTH</rptOwnerStreet2>
            <rptOwnerCity>ATLANTA</rptOwnerCity>
            <rptOwnerState>GA</rptOwnerState>
            <rptOwnerZipCode>30339</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Class A</value>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
                <footnoteId id="F3"/>
                <footnoteId id="F4"/>
            </securityTitle>
            <transactionDate>
                <value>2017-03-13</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>39457</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>19.86</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4600960</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Class A</value>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
                <footnoteId id="F5"/>
                <footnoteId id="F6"/>
            </securityTitle>
            <transactionDate>
                <value>2017-03-14</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>12543</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>19.6</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4588417</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">This Form 4 is being jointly filed by Bay Resource Partners, L.P., a Delaware limited partnership (Bay), Bay II Resource Partners, L.P., a Delaware limited partnership (Bay II), Bay Resource Partners Offshore Master Fund, L.P., an exempted limited partnership organized under the laws of the Cayman Islands (Offshore Fund), GMT Capital Corp., a Georgia corporation (GMT Capital), and Thomas E. Claugus, a United States citizen (Claugus). The foregoing persons are hereinafter sometimes collectively referred to as the Reporting Persons.</footnote>
        <footnote id="F2">GMT Capital, the general partner of Bay and Bay II has the power to direct the affairs of Bay and Bay II, including the voting and disposition of shares. As the discretionary investment manager of the Offshore Fund and certain other accounts, GMT Capital has power to direct the voting and disposition of shares held by the Offshore Fund and such accounts. Mr. Claugus is the President of GMT Capital and in
that capacity directs the operations of each of Bay and Bay II and the voting and disposition of shares held by the Offshore Fund and separate client accounts managed by GMT Capital. GMT Capital and Mr. Claugus may be deemed to beneficially own indirect pecuniary interest as the result of performance-based fees and profit allocations. Each of GMT Capital and Mr. Claugus disclaims such beneficial ownership
except to the extent ultimately realized.</footnote>
        <footnote id="F3">The aggregate number of shares of common stock sold was 39,457 shares and such shares were sold by the Reporting Persons in the following amounts: Bay = 10,800 shares; Bay II = 8,300 shares; Offshore Fund = 18,157 shares; GMT Capital = 700 shares; Claugus = 1,500 shares.</footnote>
        <footnote id="F4">4,600,960 shares of common stock is the aggregate number of shares of common stock owned by the Reporting Persons and is owned as follows: Bay = 1,256,910 shares directly owned by it; Bay II = 966,880 shares directly owned by it; Offshore Fund = 2,122,470 shares directly owned by it; GMT Capital = 74,800 shares of common stock beneficially owned by it with respect to separate client accounts managed by it; Claugus = 179,900 shares directly owned by him.</footnote>
        <footnote id="F5">The aggregate number of shares of common stock sold was 12,543 shares and such shares were sold by the Reporting Persons in the following amounts: Bay = 3,400 shares; Bay II = 2,600 shares; Offshore Fund = 5,843 shares; GMT Capital = 200 shares; Claugus = 500 shares.</footnote>
        <footnote id="F6">4,588,417 shares of common stock is the aggregate number of shares of common stock owned by the Reporting Persons and is owned as follows: Bay = 1,253,510 shares directly owned by it; Bay II = 964,280 shares directly owned by it; Offshore Fund = 2,116,627 shares directly owned by it; GMT Capital = 74,600 shares of common stock beneficially owned by it with respect to separate client accounts managed by it; Claugus = 179,400 shares directly owned by him.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Philip J. Meyers</signatureName>
        <signatureDate>2017-03-15</signatureDate>
    </ownerSignature>
</ownershipDocument>
