1
 
                                                                    EXHIBIT 99.3
[X] PLEASE MARK VOTES AS IN THIS EXAMPLE.
 
                            VIEWLOGIC SYSTEMS, INC.
 
1. To consider and vote upon a proposal to approve and adopt an Agreement and
   Plan of Merger, dated as of October 14, 1997, by and among Synopsys, Inc., a
   Delaware corporation ("Synopsys"), Post Acquisition Corp., a Delaware
   corporation and a wholly-owned subsidiary of Synopsys ("Sub"), and the
   Company, pursuant to which, among other things, (a) Sub will be merged with
   and into the Company, whereby the Company will be the surviving corporation
   and will become a wholly-owned subsidiary of Synopsys (the "Merger") and (b)
   each outstanding share of common stock, $0.01 par value per share, of the
   Company will be converted into the right to receive 0.6521 of a share of
   common stock, $0.01 par value per share, of Synopsys.
 
                    [ ] FOR     [ ] AGAINST     [ ] ABSTAIN
 
2. To transact such other business as may properly come before the Special
   Meeting, including any motion to adjourn to a later date to permit further
   solicitation of proxies if necessary, to establish a quorum or to obtain
   additional votes in favor of the Merger, or any postponement or adjournment
   thereof.
 
                    [ ] FOR     [ ] AGAINST     [ ] ABSTAIN
 
                                          RECORD DATE SHARES:
 
                                          Please be sure to sign and date this
                                          Proxy.
 
                                          Date
 
                                          --------------------------------------
                                                  Stockholder sign here
 
                                          --------------------------------------
                                                    Co-owner sign here
 
                                          Mark box at right if an address change
                                          has been noted on the reverse side of
                                          this card.  [ ]
DETACH CARD                                                          DETACH CARD
 
                            VIEWLOGIC SYSTEMS, INC.
 
Dear Stockholder,
 
Please take note of the important information enclosed with this Proxy Ballot.
There are a number of issues related to the management and operation of your
Corporation that require your immediate attention and approval. These are
discussed in detail in the enclosed proxy materials.
 
Your vote counts, and you are strongly encouraged to exercise your right to vote
your shares.
 
Please mark the boxes on this proxy card to indicate how your shares will be
voted. Then sign the card, detach it and return your proxy vote in the enclosed
postage paid envelope.
 
Your vote must be received prior to the Special Meeting of Stockholders to be
held on December 4, 1997.
 
Thank you in advance for your prompt consideration of these matters.
 
Sincerely,
 
Viewlogic Systems, Inc.
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                            VIEWLOGIC SYSTEMS, INC.
 
                   PROXY FOR SPECIAL MEETING OF STOCKHOLDERS
                         TO BE HELD ON DECEMBER 4, 1997
 
   This Proxy is Solicited on Behalf of the Board of Directors of the Company
 
The undersigned, revoking all prior proxies, hereby appoint(s) as proxies Ronald
R. Benanto and Peter T. Johnson, and each of them, with full power of
substitution, to represent and to vote as designated herein, all shares of stock
of Viewlogic Systems, Inc. (the "Company") which the undersigned would be
entitled to vote if present at the Special Meeting of Stockholders of the
Company to be held at the principal executive offices of the Company located at
293 Boston Post Road West, Marlboro, Massachusetts 01752, on Thursday, December
4, 1997 at 9:00 a.m., local time, and at any postponement or adjournment
thereof.
 
THIS PROXY, WHEN PROPERLY EXECUTED, WILL BE VOTED IN THE MANNER DIRECTED HEREIN
BY THE UNDERSIGNED STOCKHOLDER(S). IF NO DIRECTION IS GIVEN, THIS PROXY WILL BE
VOTED FOR PROPOSALS 1 AND 2. ATTENDANCE OF THE UNDERSIGNED AT THE MEETING OR AT
ANY POSTPONEMENT OR ADJOURNMENT THEREOF WILL NOT BE DEEMED TO REVOKE THIS PROXY
UNLESS THE UNDERSIGNED SHALL REVOKE THIS PROXY IN WRITING.
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           PLEASE VOTE, DATE AND SIGN ON REVERSE AND RETURN PROMPTLY
                           IN THE ENCLOSED ENVELOPE.
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   NOTE: Please sign exactly as name(s) appear(s) hereon. Joint owners should
   each sign. When signing as attorney, executor, administrator, trustee or
   guardian, please give full title as such. If a corporation, please sign in
   full corporate name by President or other authorized officer. For
   partnership, please sign in partnership name by authorized person.
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HAS YOUR ADDRESS CHANGED?
 
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