Maples, 27, has a 6.75 ERA in 11 appearances for the Cubs this season. It will be his fifth stint with the team. He has limited foes to a .182 batting averaging in 9 1/3 innings, over which he's struck out 14 and walked 10.
The Cubs' active roster now stands at 37 players.
The Cubs trail the NL Central-leading Cardinals by four games and are currently tied with the Brewers for the second National League wild-card spot.