¡Three Amigos!

From Wikipedia:
¡Three Amigos! is a 1986 comedy western film, produced by George Folsey, Jr., and Lorne Michaels. John Landis directed for HBO Films. Steve Martin, Chevy Chase and Martin Short star. The movie was written by Steve Martin, Lorne Michaels, and Randy Newman. Randy Newman contributed several original songs, including "The Ballad of the Three Amigos" and "My Little Buttercup", while the musical score was composed by Elmer Bernstein.