The comediennes will join the cast that already includes Rafe Spall and Simon Baker.
The film is about a mismatched couple trying to get through their first year of marriage. Byrne and Spall will be playing the married couple and the others will be the supporting characters.
Byrne appeared in the blockbuster films â€œX-Men: First Classâ€ and â€œBridesmaidsâ€ last year. She is currently on a crime drama television series â€œDamages.â€
And Faris was known for several comedic films, including the â€œScary Movieâ€ series, â€œWhatâ€™s Your Number?â€ and â€œThe House Bunny.â€ She will be appearing in â€œThe Dictatorâ€ and â€œMovie 43â€ later this year.
The film is being written and directed by Dan Mazer (â€œBrunoâ€).