<PAGE>   1
 
   As filed with the Securities and Exchange Commission on February 19, 1997
                                                      Registration No. 333-
================================================================================
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
 
                         ------------------------------
 
                                    FORM S-8
                             REGISTRATION STATEMENT
                                     UNDER
                           THE SECURITIES ACT OF 1933
 
                         ------------------------------
 
                            ILLINOIS TOOL WORKS INC.
             (Exact name of Registrant as specified in its charter)
 
<TABLE>
<S>                                            <C>
                   Delaware                                      36-1258310
           (State of incorporation)                 (I.R.S. Employer Identification No.)
</TABLE>
 
                             3600 West Lake Avenue
                         Glenview, Illinois 60025-5811
                    (Address of principal executive offices)
 
                            ILLINOIS TOOL WORKS INC.
                           1996 STOCK INCENTIVE PLAN
                            (Full title of the Plan)
 
                            Stewart S. Hudnut, Esq.
               Senior Vice President, General Counsel & Secretary
                            Illinois Tool Works Inc.
                             3600 West Lake Avenue
                         Glenview, Illinois 60025-5811
                                 (847) 724-7500
           (Name, address and telephone number of agent for service)
 
                        CALCULATION OF REGISTRATION FEE
 
<TABLE>
<CAPTION>
-------------------------------------------------------------------------------------------------------------------
                                                           PROPOSED MAXIMUM    PROPOSED MAXIMUM
                                         AMOUNT TO BE     OFFERING PRICE PER  AGGREGATE OFFERING       AMOUNT OF
TITLES OF SECURITIES TO BE REGISTERED     REGISTERED             SHARE               PRICE         REGISTRATION FEE
-------------------------------------------------------------------------------------------------------------------
<S>                                   <C>                    <C>                <C>                   <C>
Common Stock
(no par value)....................... 5,466,584 shares(1)    $83.3125 (2)       $455,434,799.50 (2)   $138,010.54
===================================================================================================================
</TABLE>
 
(1) Under the Plan, 4,533,416 shares that were previously registered remain
    available for issuance as of the date hereof.
 
(2) Computed pursuant to Rule 457(c) under the Securities Act of 1933 (the
    "Securities Act") solely for the purpose of calculating the registration fee
    based on the average of the high and low prices of the Common Stock for
    February 11, 1997, as reported by The Wall Street Journal under New York
    Stock Exchange Composite Transactions.
===============================================================================
<PAGE>   2
 
                    REGISTRATION STATEMENTS NO. 33-48060,
                   NO. 2-67362, NO. 2-43791 AND NO. 33-8510
                    ARE INCORPORATED HEREIN BY REFERENCE
 
                                    PART II
               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT
 
ITEM 3. INCORPORATION OF DOCUMENTS BY REFERENCE.
 
     Illinois Tool Works Inc. (the "Registrant") incorporates herein by
reference the following documents, as filed with the Securities and Exchange
Commission (the "Commission"):
 
     (i) the Registrant's Annual Report on Form 10-K/A for the year ended
December 31, 1995, the Registrant's Quarterly Report on Form 10-Q for the
quarters ended March 31, 1996, June 30, 1996 and September 30, 1996, and the
Registrant's Current Reports on Form 8-K dated February 21, 1996, Form 8-K/A
dated March 25, 1996 (Amend. No. 1), and Form 8-K/A dated April 30, 1996 (Amend.
No. 2);
 
     (ii) the Registrant's definitive proxy statement filed pursuant to Section
14 of the Securities Exchange Act of 1934 (the "Exchange Act") in connection
with the 1996 annual meeting of its stockholders; and
 
     (iii) the description of the Registrant's Common Stock, shares of which are
being offered hereunder, contained in the Registrant's Registration Statement on
Form S-4 dated June 6, 1995.
 
     All documents filed by the Registrant pursuant to Sections 13(a), 13(c), 14
and 15(d) of the Exchange Act subsequent to the date hereof and prior to the
filing of a post-effective amendment, which indicates that all of the securities
offered hereby have been sold or which deregisters all such securities remaining
unsold, shall be deemed to be incorporated by reference herein and to be part
hereof from the date of filing such documents.
 
ITEM 4. DESCRIPTION OF SECURITIES.
 
     The Registrant's Common Stock is registered under Section 12 of the
Exchange Act.
 
ITEM 5. INTERESTS OF NAMED EXPERTS AND COUNSEL.
 
     Stewart S. Hudnut, Senior Vice President, General Counsel & Secretary of
the Registrant, who is delivering the opinion attached hereto as Exhibit 5, owns
1,500 shares of the Registrant's Common Stock and holds options to acquire an
additional 35,000 shares of Common Stock.
 
ITEM 6. INDEMNIFICATION OF DIRECTORS AND OFFICERS.
 
     Section 145 of the Delaware General Corporation Law provides that the
Registrant may, and in some circumstances must, indemnify the directors and
officers of the Registrant against liabilities and expenses incurred by any such
person by reason of the fact that such person was serving in such capacity,
subject to certain limitations and conditions therein set forth. Substantially
similar provisions that require such indemnification are contained in Article V
of the Registrant's By-Laws. Article Thirteenth of the Registrant's Restated
Certificate of Incorporation, as amended, also contains provisions limiting the
liability of the Registrant's directors in certain instances. In addition, the
Registrant has purchased insurance as permitted by Delaware law on behalf of
directors, officers, employees or agents, which may cover liabilities under the
Securities Act.
 
ITEM 7. EXEMPTION FROM REGISTRATION CLAIMED.
 
     Not applicable.
<PAGE>   3
 
ITEM 8. EXHIBITS.
 
<TABLE>
<CAPTION>
EXHIBIT
NUMBER                  DESCRIPTION
-------                 -----------
<C>        <S>
  4.1      Illinois Tool Works Inc. 1996 Stock Incentive Plan.

  4.2      Restated Certificate of Incorporation of Illinois Tool Works
           Inc., filed as Exhibit 4(a) to the Registrant's Registration
           Statement on Form S-8 (Registration Statement No. 33-53517)
           filed with the Commission on May 6, 1994, and incorporated
           herein by reference.

  4.3      By-Laws of Illinois Tool Works Inc., as amended, filed as
           Exhibit 4.3 to the Registrant's Registration Statement on
           Form S-8 (Registration Statement No. 333-17473) filed with
           the Commission on December 9, 1996, and incorporated herein
           by reference.

  5        Opinion of Stewart S. Hudnut, Senior Vice President, General
           Counsel & Secretary regarding the validity of the shares of
           Common Stock being registered.

 23.1      Consent of Arthur Andersen LLP.

 23.2      Consent of Stewart S. Hudnut (included in Exhibit 5).

 24        Powers of Attorney of directors and certain officers of the
           Registrant are included on the signature page.
</TABLE>
 
ITEM 9. UNDERTAKINGS.
 
     (a) The Registrant hereby undertakes:
 
          (1) To file, during any period in which offers or sales are being
     made, a post-effective amendment to this Registration Statement to include
     any material information with respect to the plan of distribution not
     previously disclosed in the Registration Statement or any material change
     to such information in the Registration Statement.
 
          (2) That, for the purpose of determining any liability under the
     Securities Act, each such post-effective amendment shall be deemed to be a
     new registration statement relating to the securities offered therein, and
     the offering of such securities at that time shall be deemed to be the
     initial bona fide offering thereof.
 
          (3) To remove from registration by means of a post-effective amendment
     any of the securities being registered which remain unsold at the
     termination of the offering.
 
          (b) That, for purposes of determining any liability under the
     Securities Act, each filing of the Registrant's annual report pursuant to
     Section 13(a) or Section 15(d) of the Exchange Act that is incorporated by
     reference in the Registration Statement shall be deemed to be a new
     registration statement relating to the securities offered therein, and the
     offering of such securities at that time shall be deemed to be the initial
     bona fide offering thereof.
 
          (c) Insofar as indemnification for liabilities arising under the
     Securities Act may be permitted to directors, officers and controlling
     persons of the Registrant pursuant to the foregoing provisions, or
     otherwise, the Registrant has been advised that in the opinion of the
     Commission such indemnification is against public policy as expressed in
     the Securities Act and is, therefore, unenforceable. In the event that a
     claim for indemnification against such liabilities (other than the payment
     by the Registrant of expenses incurred or paid by a director, officer or
     controlling person of the Registrant in the successful defense of any
     action, suit or proceeding) is asserted by such director, officer or
     controlling person in connection with the securities being registered, the
     Registrant will, unless in the opinion of its counsel the matter has been
     settled by controlling precedent, submit to a court of appropriate
     jurisdiction the question of whether such indemnification by it is against
     public policy as expressed in the Securities Act and will be governed by
     the final adjudication of such issue.
 
                                        2
<PAGE>   4
 
                                   SIGNATURES
 
     Pursuant to the requirements of the Securities Act, the Registrant
certifies that it has reasonable grounds to believe that it meets all of the
requirements for filing on Form S-8 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of Glenview, State of Illinois, on February 14, 1997.
 
                                          ILLINOIS TOOL WORKS INC.
 
                                          By:      /s/ STEWART S. HUDNUT
                                            ------------------------------------
                                                     Stewart S. Hudnut,
                                                   Senior Vice President,
                                                General Counsel & Secretary
 
                               POWER OF ATTORNEY
 
     Each of the undersigned officers and directors of the Registrant hereby
constitutes and appoints W. James Farrell, Michael W. Gregg, John Karpan and
Stewart S. Hudnut and each of them, his true and lawful attorneys with full
power to them and to each of them singly, to sign, in any and all capacities,
any and all amendments to this Registration Statement, including post-effective
amendments, to file the same with all exhibits thereto, and other documents in
connection therewith, with the Commission under the Securities Act.
 
     Pursuant to the requirements of the Securities Act, this Registration
Statement has been signed by the following persons in the capacities indicated
on February 14, 1997.
 
<TABLE>
<CAPTION>
                      SIGNATURE                                              CAPACITY
                      ---------                                              --------
<C>                                                    <S>
 
                /s/ W. JAMES FARRELL                   Chairman and Chief Executive Officer and Director
-----------------------------------------------------  (Principal Executive Officer)
                  W. James Farrell
 
                /s/ MICHAEL W. GREGG                   Senior Vice President and Controller
-----------------------------------------------------  (Principal Financial and Accounting Officer)
                  Michael W. Gregg
 
              /s/ JULIUS W. BECTON, JR.                Director
-----------------------------------------------------
                Julius W. Becton, Jr.
 
                /s/ MICHAEL J. BIRCK                   Director
-----------------------------------------------------
                  Michael J. Birck
 
              /s/ MARVIN D. BRAILSFORD                 Director
-----------------------------------------------------
                Marvin D. Brailsford
 
                   /s/ SUSAN CROWN                     Director
-----------------------------------------------------
                     Susan Crown
 
               /s/ H. RICHARD CROWTHER                 Director
-----------------------------------------------------
                 H. Richard Crowther
 
                /s/ L. RICHARD FLURY                   Director
-----------------------------------------------------
                  L. Richard Flury
</TABLE>
 
                                        3
<PAGE>   5
                      SIGNATURE                        CAPACITY
                      ---------                        --------

                /s/ RICHARD M. JONES                   Director
-----------------------------------------------------
                  Richard M. Jones
 
                /s/ GEORGE D. KENNEDY                  Director
-----------------------------------------------------
                  George D. Kennedy
 
                 /s/ RICHARD H. LEET                   Director
-----------------------------------------------------
                   Richard H. Leet
 
               /s/ ROBERT C. MCCORMACK                 Director
-----------------------------------------------------
                 Robert C. McCormack
 
                /s/ PHILLIP B. ROONEY                  Director
-----------------------------------------------------
                  Phillip B. Rooney
 
                 /s/ HAROLD B. SMITH                   Director
-----------------------------------------------------
                   Harold B. Smith
 
                 /s/ ORMAND J. WADE                    Director
-----------------------------------------------------
                   Ormand J. Wade
 
                                        4
[{"type": "S-8", "sequence": "1", "description": "FORM S-8", "secsgml_size_bytes": 15140}]
{"company-data": {"conformed-name": "ILLINOIS TOOL WORKS INC", "cik": "0000049826", "assigned-sic": "3089", "irs-number": "361258310", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-22035", "film-number": "97538828"}, "business-address": {"street1": "3600 W LAKE AVE", "city": "GLENVIEW", "state": "IL", "zip": "60025-5811", "phone": "8477247500"}, "mail-address": {"street1": "3600 WEST LAKE AVENUE", "city": "GLENVIEW", "state": "IL", "zip": "60025-5811"}}
1
 
   As filed with the Securities and Exchange Commission on February 19, 1997
                                                      Registration No. 333-
================================================================================
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
 
                         ------------------------------
 
                                    FORM S-8
                             REGISTRATION STATEMENT
                                     UNDER
                           THE SECURITIES ACT OF 1933
 
                         ------------------------------
 
                            ILLINOIS TOOL WORKS INC.
             (Exact name of Registrant as specified in its charter)
Delaware                                      36-1258310
           (State of incorporation)                 (I.R.S. Employer Identification No.)
3600 West Lake Avenue
                         Glenview, Illinois 60025-5811
                    (Address of principal executive offices)
 
                            ILLINOIS TOOL WORKS INC.
                           1996 STOCK INCENTIVE PLAN
                            (Full title of the Plan)
 
                            Stewart S. Hudnut, Esq.
               Senior Vice President, General Counsel & Secretary
                            Illinois Tool Works Inc.
                             3600 West Lake Avenue
                         Glenview, Illinois 60025-5811
                                 (847) 724-7500
           (Name, address and telephone number of agent for service)
 
                        CALCULATION OF REGISTRATION FEE
-------------------------------------------------------------------------------------------------------------------
                                                           PROPOSED MAXIMUM    PROPOSED MAXIMUM
                                         AMOUNT TO BE     OFFERING PRICE PER  AGGREGATE OFFERING       AMOUNT OF
TITLES OF SECURITIES TO BE REGISTERED     REGISTERED             SHARE               PRICE         REGISTRATION FEE
-------------------------------------------------------------------------------------------------------------------
Common Stock
(no par value)....................... 5,466,584 shares(1)    $83.3125 (2)       $455,434,799.50 (2)   $138,010.54
===================================================================================================================
(1) Under the Plan, 4,533,416 shares that were previously registered remain
    available for issuance as of the date hereof.
 
(2) Computed pursuant to Rule 457(c) under the Securities Act of 1933 (the
    "Securities Act") solely for the purpose of calculating the registration fee
    based on the average of the high and low prices of the Common Stock for
    February 11, 1997, as reported by The Wall Street Journal under New York
    Stock Exchange Composite Transactions.
===============================================================================
2
 
                    REGISTRATION STATEMENTS NO. 33-48060,
                   NO. 2-67362, NO. 2-43791 AND NO. 33-8510
                    ARE INCORPORATED HEREIN BY REFERENCE
 
                                    PART II
               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT
 
ITEM 3. INCORPORATION OF DOCUMENTS BY REFERENCE.
 
     Illinois Tool Works Inc. (the "Registrant") incorporates herein by
reference the following documents, as filed with the Securities and Exchange
Commission (the "Commission"):
 
     (i) the Registrant's Annual Report on Form 10-K/A for the year ended
December 31, 1995, the Registrant's Quarterly Report on Form 10-Q for the
quarters ended March 31, 1996, June 30, 1996 and September 30, 1996, and the
Registrant's Current Reports on Form 8-K dated February 21, 1996, Form 8-K/A
dated March 25, 1996 (Amend. No. 1), and Form 8-K/A dated April 30, 1996 (Amend.
No. 2);
 
     (ii) the Registrant's definitive proxy statement filed pursuant to Section
14 of the Securities Exchange Act of 1934 (the "Exchange Act") in connection
with the 1996 annual meeting of its stockholders; and
 
     (iii) the description of the Registrant's Common Stock, shares of which are
being offered hereunder, contained in the Registrant's Registration Statement on
Form S-4 dated June 6, 1995.
 
     All documents filed by the Registrant pursuant to Sections 13(a), 13(c), 14
and 15(d) of the Exchange Act subsequent to the date hereof and prior to the
filing of a post-effective amendment, which indicates that all of the securities
offered hereby have been sold or which deregisters all such securities remaining
unsold, shall be deemed to be incorporated by reference herein and to be part
hereof from the date of filing such documents.
 
ITEM 4. DESCRIPTION OF SECURITIES.
 
     The Registrant's Common Stock is registered under Section 12 of the
Exchange Act.
 
ITEM 5. INTERESTS OF NAMED EXPERTS AND COUNSEL.
 
     Stewart S. Hudnut, Senior Vice President, General Counsel & Secretary of
the Registrant, who is delivering the opinion attached hereto as Exhibit 5, owns
1,500 shares of the Registrant's Common Stock and holds options to acquire an
additional 35,000 shares of Common Stock.
 
ITEM 6. INDEMNIFICATION OF DIRECTORS AND OFFICERS.
 
     Section 145 of the Delaware General Corporation Law provides that the
Registrant may, and in some circumstances must, indemnify the directors and
officers of the Registrant against liabilities and expenses incurred by any such
person by reason of the fact that such person was serving in such capacity,
subject to certain limitations and conditions therein set forth. Substantially
similar provisions that require such indemnification are contained in Article V
of the Registrant's By-Laws. Article Thirteenth of the Registrant's Restated
Certificate of Incorporation, as amended, also contains provisions limiting the
liability of the Registrant's directors in certain instances. In addition, the
Registrant has purchased insurance as permitted by Delaware law on behalf of
directors, officers, employees or agents, which may cover liabilities under the
Securities Act.
 
ITEM 7. EXEMPTION FROM REGISTRATION CLAIMED.
 
     Not applicable.
3
 
ITEM 8. EXHIBITS.
EXHIBIT
NUMBER                  DESCRIPTION
-------                 -----------
4.1      Illinois Tool Works Inc. 1996 Stock Incentive Plan.

  4.2      Restated Certificate of Incorporation of Illinois Tool Works
           Inc., filed as Exhibit 4(a) to the Registrant's Registration
           Statement on Form S-8 (Registration Statement No. 33-53517)
           filed with the Commission on May 6, 1994, and incorporated
           herein by reference.

  4.3      By-Laws of Illinois Tool Works Inc., as amended, filed as
           Exhibit 4.3 to the Registrant's Registration Statement on
           Form S-8 (Registration Statement No. 333-17473) filed with
           the Commission on December 9, 1996, and incorporated herein
           by reference.

  5        Opinion of Stewart S. Hudnut, Senior Vice President, General
           Counsel & Secretary regarding the validity of the shares of
           Common Stock being registered.

 23.1      Consent of Arthur Andersen LLP.

 23.2      Consent of Stewart S. Hudnut (included in Exhibit 5).

 24        Powers of Attorney of directors and certain officers of the
           Registrant are included on the signature page.
ITEM 9. UNDERTAKINGS.
 
     (a) The Registrant hereby undertakes:
 
          (1) To file, during any period in which offers or sales are being
     made, a post-effective amendment to this Registration Statement to include
     any material information with respect to the plan of distribution not
     previously disclosed in the Registration Statement or any material change
     to such information in the Registration Statement.
 
          (2) That, for the purpose of determining any liability under the
     Securities Act, each such post-effective amendment shall be deemed to be a
     new registration statement relating to the securities offered therein, and
     the offering of such securities at that time shall be deemed to be the
     initial bona fide offering thereof.
 
          (3) To remove from registration by means of a post-effective amendment
     any of the securities being registered which remain unsold at the
     termination of the offering.
 
          (b) That, for purposes of determining any liability under the
     Securities Act, each filing of the Registrant's annual report pursuant to
     Section 13(a) or Section 15(d) of the Exchange Act that is incorporated by
     reference in the Registration Statement shall be deemed to be a new
     registration statement relating to the securities offered therein, and the
     offering of such securities at that time shall be deemed to be the initial
     bona fide offering thereof.
 
          (c) Insofar as indemnification for liabilities arising under the
     Securities Act may be permitted to directors, officers and controlling
     persons of the Registrant pursuant to the foregoing provisions, or
     otherwise, the Registrant has been advised that in the opinion of the
     Commission such indemnification is against public policy as expressed in
     the Securities Act and is, therefore, unenforceable. In the event that a
     claim for indemnification against such liabilities (other than the payment
     by the Registrant of expenses incurred or paid by a director, officer or
     controlling person of the Registrant in the successful defense of any
     action, suit or proceeding) is asserted by such director, officer or
     controlling person in connection with the securities being registered, the
     Registrant will, unless in the opinion of its counsel the matter has been
     settled by controlling precedent, submit to a court of appropriate
     jurisdiction the question of whether such indemnification by it is against
     public policy as expressed in the Securities Act and will be governed by
     the final adjudication of such issue.
 
                                        2
4
 
                                   SIGNATURES
 
     Pursuant to the requirements of the Securities Act, the Registrant
certifies that it has reasonable grounds to believe that it meets all of the
requirements for filing on Form S-8 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of Glenview, State of Illinois, on February 14, 1997.
 
                                          ILLINOIS TOOL WORKS INC.
 
                                          By:      /s/ STEWART S. HUDNUT
                                            ------------------------------------
                                                     Stewart S. Hudnut,
                                                   Senior Vice President,
                                                General Counsel & Secretary
 
                               POWER OF ATTORNEY
 
     Each of the undersigned officers and directors of the Registrant hereby
constitutes and appoints W. James Farrell, Michael W. Gregg, John Karpan and
Stewart S. Hudnut and each of them, his true and lawful attorneys with full
power to them and to each of them singly, to sign, in any and all capacities,
any and all amendments to this Registration Statement, including post-effective
amendments, to file the same with all exhibits thereto, and other documents in
connection therewith, with the Commission under the Securities Act.
 
     Pursuant to the requirements of the Securities Act, this Registration
Statement has been signed by the following persons in the capacities indicated
on February 14, 1997.
SIGNATURE                                              CAPACITY
                      ---------                                              --------
/s/ W. JAMES FARRELL                   Chairman and Chief Executive Officer and Director
-----------------------------------------------------  (Principal Executive Officer)
                  W. James Farrell
 
                /s/ MICHAEL W. GREGG                   Senior Vice President and Controller
-----------------------------------------------------  (Principal Financial and Accounting Officer)
                  Michael W. Gregg
 
              /s/ JULIUS W. BECTON, JR.                Director
-----------------------------------------------------
                Julius W. Becton, Jr.
 
                /s/ MICHAEL J. BIRCK                   Director
-----------------------------------------------------
                  Michael J. Birck
 
              /s/ MARVIN D. BRAILSFORD                 Director
-----------------------------------------------------
                Marvin D. Brailsford
 
                   /s/ SUSAN CROWN                     Director
-----------------------------------------------------
                     Susan Crown
 
               /s/ H. RICHARD CROWTHER                 Director
-----------------------------------------------------
                 H. Richard Crowther
 
                /s/ L. RICHARD FLURY                   Director
-----------------------------------------------------
                  L. Richard Flury
3
5
                      SIGNATURE                        CAPACITY
                      ---------                        --------

                /s/ RICHARD M. JONES                   Director
-----------------------------------------------------
                  Richard M. Jones
 
                /s/ GEORGE D. KENNEDY                  Director
-----------------------------------------------------
                  George D. Kennedy
 
                 /s/ RICHARD H. LEET                   Director
-----------------------------------------------------
                   Richard H. Leet
 
               /s/ ROBERT C. MCCORMACK                 Director
-----------------------------------------------------
                 Robert C. McCormack
 
                /s/ PHILLIP B. ROONEY                  Director
-----------------------------------------------------
                  Phillip B. Rooney
 
                 /s/ HAROLD B. SMITH                   Director
-----------------------------------------------------
                   Harold B. Smith
 
                 /s/ ORMAND J. WADE                    Director
-----------------------------------------------------
                   Ormand J. Wade
 
                                        4