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

    <schemaVersion>X0201</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2004-04-21</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000853273</issuerCik>
        <issuerName>BORLAND SOFTWARE CORP</issuerName>
        <issuerTradingSymbol>BORL</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001268913</rptOwnerCik>
            <rptOwnerName>ELLOY BRIAN</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O BORLAND SOFTWARE CORP</rptOwnerStreet1>
            <rptOwnerStreet2>100 ENTERPRISE WAY</rptOwnerStreet2>
            <rptOwnerCity>SCOTTS VALLEY</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>950663247</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Sr. VP of Software Products</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>26250</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>9.37</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2004-04-21</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>110000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>9.37</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2005-04-21</value>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <value>2014-04-21</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>110000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>110000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Includes 1,250 shares acquired pursuant to the Borland Software Corporation 1999 Employee Stock Purchase Plan on November 28, 2003.</footnote>
        <footnote id="F2">The shares subject to the option vest as follows: 25% on April 21, 2005 and the remaining 75% in equal installments upon the completion of each additional month of continued employment with Borland over the 36 months thereafter, with such vesting to accelerate 100% should Mr. Elloy's employment terminate, under the circumstances specified in his employment agreement, within 12 months after a Change in Control of Borland (as such term is defined in the stock plan pursuant to which such option was granted).</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Timothy Stevens, Attorney-in-fact</signatureName>
        <signatureDate>2004-04-23</signatureDate>
    </ownerSignature>
</ownershipDocument>

