The Cubs activated Williams (abdomen) from the 10-day IL on Tuesday, Meghan Montemurro of the Chicago Tribune reports.
The righty returns to the Cubs after lasting five scoreless innings Friday in his second rehab outing with Triple-A Iowa. Williams' 5.36 ERA this season is not pretty, and Alec Mills has been decent of late as the fifth starter, so it's possible the former shifts to the bullpen.