March 1, 1999



Morgan Stanley Dean Witter Income Builder Fund
Two World Trade Center
New York, New York  10048

Ladies and Gentlemen:

                  This opinion is being furnished to Morgan Stanley Dean Witter
Income Builder Fund, a Massachusetts business trust (the "Trust"), in
connection with the Registration Statement on Form N-14 (the "Registration
Statement") under the Securities Act of 1933, as amended (the "1933 Act"), to
be filed by the Trust in connection with the acquisition by the Trust of
substantially all the assets of TCW/DW Income and Growth Fund ("Income &
Growth"), in exchange for shares of beneficial interest, par value $.01, of the
Trust ("Shares") and the assumption by the Trust of certain stated liabilities
of Income & Growth pursuant to an Agreement and Plan of Reorganization dated as
of February 25, 1999, between the Trust and Income & Growth (the
"Reorganization Agreement"). We have examined such statutes, regulations,
corporate records and other documents and reviewed such questions of law as we
deemed necessary or appropriate for the purposes of this opinion.

                  As to matters of Massachusetts law contained in this opinion,
we have relied upon the opinion of Lane Altman & Owens LLP, dated March 1,
1999.

                  Based upon the foregoing, we are of the opinion that the
Shares when issued, as described in the Reorganization Agreement, will be duly
authorized and, assuming receipt of the consideration to be paid therefor, upon
delivery as provided in the Reorganization Agreement, will be legally issued,
fully paid and non-assessable (except for the potential liability of
shareholders described in the Trust's current Prospectus under the caption
"Additional Information").

                  We hereby consent to the filing of this opinion as an exhibit
to the Registration Statement and to the reference to us under the caption
"Legal Matters" in the Prospectus forming a part of the Registration Statement.
We do not thereby admit that we are within the category of persons whose
consent is required under Section 7 of the 1933 Act or the rules and
regulations of the Securities and Exchange Commission thereunder.

                                            Very truly yours,

                                            /s/ Gordon Altman Butowsky Weitzen
                                                     Shalov & Wein