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

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2005-07-01</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000853273</issuerCik>
        <issuerName>BORLAND SOFTWARE CORP</issuerName>
        <issuerTradingSymbol>pwd5sie*</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001177083</rptOwnerCik>
            <rptOwnerName>HOOPER WILLIAM K</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>100 ENTERPRISE WAY</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SCOTTS VALLEY</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>95066-3249</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>6.88</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2005-07-01</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>21500</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>6.88</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2005-07-01</value>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2015-07-01</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>21500</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>21500</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Any or all of the shares subject to the option are immediately exercisable however, any unvested shares purchased under the option shall be subject to repurchase by the issuer.  The shares subject to the option shall vest, and the issuer's right of repurchase as to the shares shall lapse, in accordance with the following schedule:  one-third (1/3) of the shares on the first anniversary of the date of grant, and one-thirty-sixth (1/36) of the shares each month thereafter for the twenty-four (24) months following the first anniversary of the date of grant, such that all of the shares subject to the option shall be vested, and the issuer's right of repurchase shall have fully lapsed, on the third anniversary of the date of grant, assuming the Reporting Person's continuing service on the Board of Directors of the issuer at each vesting date.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Timothy J. Stevens, Attorney-in-Fact for William K. Hooper</signatureName>
        <signatureDate>2005-07-01</signatureDate>
    </ownerSignature>
</ownershipDocument>
