Ferrell and Galifianakis play feuding North Carolina politicians in Dog Fight, but The Wrap reports that Aykroyd's role hasn't yet been revealed.
Adam McKay will serve as a producer for the film alongside Ferrell and Galifianakis, while Austin Powers helmer Jay Roach is to direct the film.
Aykroyd joins Dylan McDermott, Jason Sudeikis, Brian Cox and John Lithgow in Dog Fight's cast.
Dog Fight opens on August 10, 2012 in US cinemas. A UK release date hasn't been announced.
Ferrell recently filmed a series of television advertisements for Old Milwaukee beer.
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Watch Will Ferrell in the trailer for Casa de mi Padre, opening in US cinemas on March 16, 2012, below: