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                                                                   EXHIBIT 10.15



                                 SYNOPSYS, INC.
                  1994 NON-EMPLOYEE DIRECTORS STOCK OPTION PLAN

                (REFLECTING AMENDMENTS THROUGH FEBRUARY 28, 1997)

         I.          PURPOSE OF THE PLAN

                     This 1994 Non-Employee Directors Stock Option Plan (the
"Plan") is intended to promote the interests of Synopsys, Inc., a Delaware
corporation (the "Corporation"), by providing the non-employee members of the
Board of Directors with the opportunity to acquire a proprietary interest, or
otherwise increase their proprietary interest, in the Corporation as an
incentive for them to remain in the service of the Corporation.

        II.          DEFINITIONS

                     For purposes of the Plan, the following definitions shall
be in effect:

                     ANNUAL MEETING: the annual meeting of the Corporation's
stockholders.

                     BOARD:  the Corporation's Board of Directors.

                     CODE:  the Internal Revenue Code of 1986, as amended.

                     COMMON STOCK:  shares of the Corporation's common stock.

                     CHANGE IN CONTROL: a change in ownership or control of the
Corporation effected through either of the following transactions:

                               a. any person or related group of persons (other
           than the Corporation or a person that directly or indirectly
           controls, is controlled by, or is under common control with, the
           Corporation) directly or indirectly acquires beneficial ownership
           (within the meaning of Rule 13d-3 of the Securities Exchange Act of
           1934, as amended) of securities possessing more than fifty percent
           (50%) of the total combined voting power of the Corporation's
           outstanding securities pursuant to a tender or exchange offer made
           directly to the Corporation's stockholders which the Board does not
           recommend such stockholders to accept; or

                               b. there is a change in the composition of the
           Board over a period of twenty-four (24) consecutive months or less
           such that a majority of the Board members ceases, by reason of one or
           more contested elections for Board membership, to be comprised of
           individuals who either (A) have been Board members continuously since
           the beginning of such period or (B) have been elected or nominated
           for election as Board members during such period by at least a
           majority of the Board members described in clause (A) who were still
           in office at the time such election or nomination was approved by the
           Board.

                     CORPORATE  TRANSACTION:  any of the following  stockholder-
approved transactions to which the Corporation is a party:



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                                a. a merger or consolidation in which the
            Corporation is not the surviving entity, except for a transaction
            the principal purpose of which is to change the State of the
            Corporation's incorporation,

                                b. the sale, transfer or other disposition of
            all or substantially all of the assets of the Corporation in
            complete liquidation or dissolution of the Corporation, or

                               c. any reverse merger in which the Corporation is
           the surviving entity but in which securities possessing more than
           fifty percent (50%) of the total combined voting power of the
           Corporation's outstanding securities are transferred to holders
           different from those who held such securities immediately prior to
           such merger.

                     EFFECTIVE DATE:  October 27, 1994, the date on which the 
Plan was adopted by the Board.

                     FAIR MARKET VALUE:  the Fair Market Value per share of 
Common Stock determined in accordance with the following provisions:

                               a. If the Common Stock is not at the time listed
           or admitted to trading on any national securities exchange but is
           traded on the Nasdaq National Market, the Fair Market Value shall be
           the closing selling price per share on the date in question, as such
           price is reported by the National Association of Securities Dealers
           on the Nasdaq National Market or any successor system. If there is no
           reported closing selling price for the Common Stock on the date in
           question, then the closing selling price on the last preceding date
           for which such quotation exists shall be determinative of Fair Market
           Value.

                               b. If the Common Stock is at the time listed or
           admitted to trading on any national securities exchange, then the
           Fair Market Value shall be the closing selling price per share on the
           date in question on the exchange serving as the primary market for
           the Common Stock, as such price is officially quoted in the composite
           tape of transactions on such exchange. If there is no reported sale
           of Common Stock on such exchange on the date in question, then the
           Fair Market Value shall be the closing selling price on the exchange
           on the last preceding date for which such quotation exists.

                     HOSTILE TAKE-OVER:  a change in ownership of the 
Corporation effected through the following transaction:

                               a. any person or related group of persons (other
           than the Corporation or a person that directly or indirectly
           controls, is controlled by, or is under common control with, the
           Corporation) directly or indirectly acquires beneficial ownership
           (within the meaning of Rule 13d-3 of the Securities Exchange Act of
           1934, as amended) of securities possessing more than fifty percent
           (50%) of the total combined voting power of the Corporation's
           outstanding securities pursuant to a tender or exchange offer made
           directly to the Corporation's stockholders which the Board does not
           recommend such stockholders to accept, and



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                               b. more than fifty percent (50%) of the
           securities so acquired in such tender or exchange offer are accepted
           from holders other than the officers and directors of the Corporation
           subject to the short-swing profit restrictions of Section 16 of the
           1934 Act.

                     1934 ACT: the Securities Exchange Act of 1934, as amended.

                     OPTIONEE: any person to whom an option is granted under the
Plan.

                     PERMANENT DISABILITY OR PERMANENTLY DISABLED: the inability
of the Optionee to engage in any substantial gainful activity by reason of any
medically determinable physical or mental impairment expected to result in death
or to be of continuous duration of twelve (12) months or more.

                     TAKE-OVER PRICE: the greater of (a) the Fair Market Value
per share of Common Stock on the date the option is surrendered to the
Corporation in connection with a Hostile Take-Over or (b) the highest reported
price per share of Common Stock paid by the tender offeror in effecting such
Hostile Take-Over.

       III.          ADMINISTRATION OF THE PLAN

                     The terms and conditions of each automatic option grant
(including the timing and pricing of the option grant) shall be determined by
the express terms and conditions of the Plan, and neither the Board nor any
committee of the Board shall exercise any discretionary functions with respect
to option grants made pursuant to the Plan.

        IV.          STOCK SUBJECT TO THE PLAN

                     A. Shares of the Corporation's Common Stock shall be
available for issuance under the Plan and shall be drawn from either the
Corporation's authorized but unissued shares of Common Stock or from reacquired
shares of Common Stock, including shares repurchased by the Corporation on the
open market. The number of shares of Common Stock reserved for issuance over the
term of the Plan shall initially be fixed at 100,000 shares.

                     B. The number of shares of Common Stock available for
issuance under the Plan shall automatically increase on the first trading day of
each calendar year during the term of the Plan, beginning with the 1996 calendar
year, by an additional 12,500 shares.

                     C. Should one or more outstanding options under this Plan
expire or terminate for any reason prior to exercise in full, then the shares
subject to the portion of each option not so exercised shall be available for
subsequent option grant under the Plan. Shares subject to any option or portion
thereof surrendered in accordance with Article VII and all share issuances under
the Plan, whether or not the shares are subsequently repurchased by the
Corporation pursuant to its repurchase rights under the Plan, shall reduce on a
share-for-share basis the number of shares of Common Stock available for
subsequent option grant under the Plan. In addition, should the exercise price
of an outstanding option under the Plan be paid with shares of Common Stock,
then the number of shares of Common Stock available for issuance under the Plan
shall be reduced by the gross number of shares for which the option is
exercised, and not by the net number of shares of Common Stock actually issued
to the holder of such option.

                     D. Should any change be made to the Common Stock issuable
under the Plan by reason of any stock split, stock dividend, recapitalization,
combination of shares, exchange of 



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shares or other change affecting the outstanding Common Stock as a class without
the Corporation's receipt of consideration, then appropriate adjustments shall
be made to (i) the maximum number and/or class of securities issuable under the
Plan, (ii) the number and/or class of securities by which the share reserve is
to increase automatically each calendar year, (iii) the number and/or class of
securities for which automatic option grants are to be subsequently made to each
newly-elected or continuing non-employee Board member under the Plan, and (iv)
the number and/or class of securities and price per share in effect under each
option outstanding under the Plan. The adjustments to the outstanding options
shall be made by the Board in a manner which shall preclude the enlargement or
dilution of rights and benefits under such options and shall be final, binding
and conclusive.

         V.          ELIGIBILITY

                     A. Eligible Optionees. The individuals eligible to receive
automatic option grants pursuant to the provisions of this Plan shall be limited
to (i) those individuals serving as non-employee Board members on the Effective
Date who have indicated their intention to stand for re-election to the Board at
the 1995 Annual Meeting and who have not otherwise previously received a stock
option grant from the Corporation, (ii) those individuals who are first elected
or appointed as non-employee Board members after the Effective Date, whether
through appointment by the Board or election by the Corporation's stockholders,
and (iii) those individuals who are re-elected as non-employee Board members at
one or more Annual Meetings held after the Effective Date. A non-employee Board
member shall not be eligible to receive the initial automatic option grant under
clause (i) or clause (ii) if such individual has previously been in the employ
of the Corporation (or any parent or subsidiary). However, a non-employee Board
member shall be eligible to receive one or more clause (iii) option grants,
whether or not he or she has previously been in the employ of the Corporation
(or any parent or subsidiary). Each non-employee Board member eligible to
participate in the Plan pursuant to the foregoing criteria is hereby designated
an Eligible Director.

                     B. Limitation. Except for the grants to be made pursuant to
this Plan, non-employee Board members shall not be eligible to receive any stock
options, stock appreciation rights, direct stock issuances or other stock awards
under this Plan or any other stock plan of the Corporation or any parent or
subsidiary.

        VI.          TERMS AND CONDITIONS OF AUTOMATIC OPTION GRANTS

                     A. Grant Date. Option grants shall be made on the dates
specified below:

                     - Each individual serving as an Eligible Director on the
           Effective Date who has indicated his or her intention to stand for
           re-election to the Board at the 1995 Annual Meeting and who has not
           otherwise previously received a stock option grant from the
           Corporation year shall automatically be granted at that time a
           non-statutory stock option to purchase 20,000 shares of Common Stock.

                     - Each individual who first becomes an Eligible Director
           after the Effective Date, whether through election by the
           Corporation's stockholders or appointment by the Board, shall
           automatically be granted, at the time of such initial election or
           appointment, a non-statutory option to purchase 20,000 shares of
           Common Stock.

                     - On the date of each Annual Meeting, beginning with the
           1995 Annual Meeting, each Eligible Director who is re-elected to the
           Board at that Annual 



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           Meeting shall automatically be granted a non-statutory option to
           purchase an additional 8,000 shares of Common Stock.

                     There shall be no limit on the number of such annual
8,000-share option grants any one Eligible Director may receive over his or her
period of continued Board service.

                     B. Exercise Price. The exercise price per share of Common
Stock subject to each automatic option grant shall be equal to one hundred
percent (100%) of the Fair Market Value per share of Common Stock on the
automatic grant date.

                     C.        Payment.

                     The exercise price shall become immediately due upon
exercise of the option and shall be payable in one of the alternative forms
specified below:

                                      (i) full payment in cash or check made
            payable to the Corporation's order; or

                                      (ii) full payment in shares of Common
            Stock held for the requisite period necessary to avoid a charge to
            the Corporation's earnings for financial-reporting purposes and
            valued at Fair Market Value on the Exercise Date (as such term is
            defined below); or

                                      (iii) full payment in a combination of
            shares of Common Stock held for the requisite period necessary to
            avoid a charge to the Corporation's earnings for financial-reporting
            purposes and valued at Fair Market Value on the Exercise Date and
            cash or check payable to the Corporation's order; or

                                      (iv) to the extent the option is exercised
            for vested shares, full payment through a broker-dealer sale and
            remittance procedure pursuant to which the non-employee Board member
            (I) shall provide irrevocable written instructions to a
            Corporation-designated brokerage firm to effect the immediate sale
            of the purchased shares and remit to the Corporation, out of the
            sale proceeds available on the settlement date, sufficient funds to
            cover the aggregate exercise price payable for the purchased shares
            and (II) shall concurrently provide written directives to the
            Corporation to deliver the certificates for the purchased shares
            directly to such brokerage firm in order to complete the sale
            transaction.

                     For purposes of this Section VI.C, the Exercise Date shall
be the date on which written notice of the option exercise is delivered to the
Corporation. Except to the extent the sale and remittance procedure specified
above is utilized in connection with the exercise of the option for vested
shares, payment of the exercise price for the purchased shares must accompany
the exercise notice. However, if the option is exercised for any unvested
shares, then the Optionee must also execute and deliver to the Corporation a
stock purchase agreement for those unvested shares which provides the
Corporation with the right to repurchase, at the exercise price paid per share,
any unvested shares held by the Optionee at the time of his or her cessation of
Board service and which precludes the sale, transfer or other disposition of any
shares purchased under the option, to the extent those shares are at the time
subject to the Corporation's repurchase right.

                     D. Exercisability/Vesting. Each automatic grant shall be
immediately exercisable for any or all of the option shares; provided, however,
that no such grant shall become exercisable in whole or in part unless the
stockholders approve this Plan at the 1995 Annual 



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Meeting. Any shares purchased under the option shall be subject to repurchase by
the Corporation, at the exercise price paid per share, upon the Optionee's
cessation of Board service prior to vesting in those shares in accordance with
the applicable schedule below.

                     - The initial automatic grant for 20,000 shares made to
           each Eligible Director shall vest, and the Corporation's repurchase
           right shall lapse, in a series of four (4) successive equal
           installments as such individual continues in Board service through
           the date immediately preceding each of the first four (4) Annual
           Meetings following the grant date of that option.

                     - Each annual 8,000-share automatic grant made to an
           Eligible Director shall vest in full, and the Corporation's
           repurchase right shall lapse in its entirety, on the date immediately
           prior to the fourth Annual Meeting following the grant date of that
           option, provided the Optionee continues in Board service through that
           vesting date.

                     Vesting of the option shares shall be subject to
acceleration as provided in Section VI.G and Article VII. In no event, however,
shall any additional option shares vest after the Optionee's cessation of Board
service.

                     E. Option Term. Each automatic grant under the Plan shall
have a maximum term of ten (10) years measured from the automatic grant date.

                     F. Non-Transferability. During the lifetime of the
Optionee, each automatic option grant, together with the limited stock
appreciation right pertaining to such option, shall be exercisable only by the
Optionee and shall not be assignable or transferable by the Optionee other than
a transfer of the option effected by will or by the laws of descent and
distribution following Optionee's death.

                     G.        Effect of Termination of Board Service.

                               1. Should the Optionee cease to serve as a Board
member for any reason (other than death or Permanent Disability) while holding
one or more automatic option grants under the Plan, then such individual shall
have a six (6)-month period following the date of such cessation of Board
service in which to exercise each such option for any or all of the option
shares in which the Optionee is vested at the time of his or her cessation of
Board service. Each such option shall immediately terminate and cease to be
outstanding, at the time of such cessation of Board service, with respect to any
option shares in which the Optionee is not otherwise at that time vested.

                               2. Should the Optionee die within six (6) months
after cessation of Board service, then any automatic option grant held by the
Optionee at the time of death may subsequently be exercised, for any or all of
the option shares in which the Optionee is vested at the time of his or her
cessation of Board service (less any option shares subsequently purchased by the
Optionee prior to death), by the personal representative of the Optionee's
estate or by the person or persons to whom the option is transferred pursuant to
the Optionee's will or in accordance with the laws of descent and distribution.
The right to exercise each such option shall lapse upon the expiration of the
twelve (12)-month period measured from the date of the Optionee's death.

                               3. Should the Optionee die or become Permanently
Disabled while serving as a Board member, then any automatic option grant held
by the Optionee at the time of his or her death or Permanent Disability may
subsequently be exercised for any or all of the option 



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shares in which the Optionee is vested at that time plus an additional number of
option shares equal to the number of option shares (if any) in which the
Optionee would have vested had he or she continued in Board service until the
next Annual Meeting. The Optionee (or the personal representative of the
Optionee's estate or the person or persons to whom the option is transferred
upon the Optionee's death) shall have the right to exercise the option for such
number of option shares at any time prior to the expiration of the twelve
(12)-month period measured from the date of the Optionee's death or Permanent
Disability.

                               4. In no event shall any automatic grant under
this Plan remain exercisable after the expiration date of the maximum ten
(10)-year option term. Upon the expiration of the applicable post-service
exercise period under subparagraphs 1 through 3 above or (if earlier) upon the
expiration of the maximum ten (10)-year option term, the automatic grant shall
terminate and cease to be outstanding for any option shares in which the
Optionee was vested at the time of his or her cessation of Board service but for
which such option was not otherwise exercised.

                     H. Stockholder Rights. The holder of an automatic option
grant shall have none of the rights of a stockholder with respect to any shares
subject to such option until such individual shall have exercised the option and
paid the exercise price for the purchased shares.

                     I. Remaining Terms. The remaining terms and conditions of
each automatic option grant shall be as set forth in the form Stock Option
Agreement attached as Exhibit A.

       VII.          SPECIAL ACCELERATION EVENTS

                     A. In the event of any Corporate Transaction, the shares of
Common Stock at the time subject to each outstanding option but not otherwise
vested shall automatically vest in full so that each such option shall,
immediately prior to the specified effective date for the Corporate Transaction,
become fully exercisable for all of the shares of Common Stock at the time
subject to that option and may be exercised for all or any portion of such
shares as fully-vested shares of Common Stock. Immediately following the
consummation of the Corporate Transaction, each automatic option grant under the
Plan shall terminate and cease to be outstanding, except to the extent assumed
by the successor corporation or its parent company.

                     B. In connection with any Change in Control of the
Corporation, the shares of Common Stock at the time subject to each outstanding
option but not otherwise vested shall automatically vest in full so that each
such option shall, immediately prior to the specified effective date for the
Change in Control, become fully exercisable for all of the shares of Common
Stock at the time subject to that option and may be exercised for all or any
portion of such shares as fully-vested shares of Common Stock. Each such option
shall remain exercisable for such fully-vested option shares until the
expiration or sooner termination of the option term or the cash-out of the
option in accordance with Section VII.C.

                     C. Upon the occurrence of a Hostile Take-Over, the Optionee
shall have a thirty (30)-day period in which to surrender to the Corporation
each automatic option grant held by him or her for a period of at least six (6)
months. The Optionee shall in return be entitled to a cash distribution from the
Corporation in an amount equal to the excess of (i) the Take-Over Price of the
shares of Common Stock at the time subject to the surrendered option (whether or
not the Optionee is otherwise at the time vested in those shares) over (ii) the
aggregate exercise price payable for such shares. Such cash distribution shall
be paid within five (5) days following the surrender of the option to the
Corporation. No approval or consent of the Board shall be required in connection
with such option surrender and cash distribution.



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                     D. The shares of Common Stock subject to each option
surrendered in connection with the Hostile Take-Over shall NOT be available for
subsequent option grant under this Plan.

                     E. The automatic option grants outstanding under the Plan
shall in no way affect the right of the Corporation to adjust, reclassify,
reorganize or otherwise change its capital or business structure or to merge,
consolidate, dissolve, liquidate or sell or transfer all or any part of its
business or assets.


      VIII.          AMENDMENT OF THE PLAN AND AWARDS

                     The Board has complete and exclusive power and authority to
amend or modify the Plan (or any component thereof) in any or all respects
whatsoever. However, (i) the Plan, together with the option grants outstanding
under the Plan, may not be amended at intervals more frequently than once every
six (6) months, other than to the extent necessary to comply with applicable
Federal income tax laws and regulations, and (ii) no such amendment or
modification shall adversely affect rights and obligations with respect to
options at the time outstanding under the Plan, unless the affected Optionees
consent to such amendment. In addition, the Board may not, without the approval
of the Corporation's stockholders, amend the Plan to (i) materially increase the
maximum number of shares issuable under the Plan or the number of shares
issuable per newly-elected or continuing Eligible Director, except for
permissible adjustments under Section IV.B., (ii) materially modify the
eligibility requirements for participation in the Plan or (iii) materially
increase the benefits accruing to participants in the Plan.

        IX.          EFFECTIVE DATE AND TERM OF PLAN

                     A. The Plan became effective immediately upon adoption by
the Board on the Effective Date, and one or more automatic option grants may be
made under the Plan at any time on or after such Effective Date. However, no
options granted under the Plan shall become exercisable in whole or in part
prior to approval of the Plan by the Corporation's stockholders at the 1995
Annual Meeting. If such approval is not obtained, then all options previously
granted under the Plan shall terminate and cease to be outstanding, and no
further option grants shall be made under the Plan.

                     B. The Plan shall terminate upon the earlier of (i) October
26, 2004 or (ii) the date on which all shares available for issuance under the
Plan shall have been issued or canceled pursuant to the exercise or cash-out of
the options granted under the Plan. If the date of termination is determined
under clause (i) above, then all option grants and unvested stock issuances
outstanding on such date shall thereafter continue to have force and effect in
accordance with the provisions of the agreements evidencing those option grants
or stock issuances.

         X.          USE OF PROCEEDS

                     Any cash proceeds received by the Corporation from the sale
of shares pursuant to option grants or share issuances under the Plan shall be
used for general corporate purposes.



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        XI.          REGULATORY APPROVALS

                     A. The implementation of the Plan, the granting of any
option under the Plan and the issuance of Common Stock upon the exercise of the
option grants made hereunder shall be subject to the Corporation's procurement
of all approvals and permits required by regulatory authorities having
jurisdiction over the Plan, the options granted under it, and the Common Stock
issued pursuant to it.

                     B. No shares of Common Stock or other assets shall be
issued or delivered under this Plan unless and until there shall have been
compliance with all applicable requirements of Federal and state securities
laws, including the filing and effectiveness of the Form S-8 registration
statement for the shares of Common Stock issuable under the Plan, and all
applicable listing requirements of any securities exchange on which the Common
Stock is then listed for trading.

       XII.          NO IMPAIRMENT OF RIGHTS

                     Neither the action of the Corporation in establishing the
Plan nor any provision of the Plan shall be construed or interpreted so as to
affect adversely or otherwise impair the right of the Corporation or the
stockholders to remove any individual from the Board at any time in accordance
with the provisions of applicable law.

      XIII.          MISCELLANEOUS PROVISIONS

                     A. The right to acquire Common Stock or other assets under
the Plan may not be assigned, encumbered or otherwise transferred by any
Optionee.

                     B. The provisions of the Plan relating to the exercise of
options and the vesting of shares shall be governed by the laws of the State of
California, as such laws are applied to contracts entered into and performed in
such State.

                     C. The provisions of the Plan shall inure to the benefit
of, and be binding upon, the Corporation and its successors or assigns, whether
by Corporate Transaction or otherwise, and the Optionees, the legal
representatives of their respective estates, their respective heirs or legatees
and their permitted assignees.

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