Saunders, who last pitched June 16, had been shelved because of a strain in his left shoulder. The 31-year-old is 4-5 with a 3.44 ERA in 13 starts this season.
Arizona optioned lefty Patrick Corbin to Triple-A Reno, where he will return to the starting rotation. Corbin started five games for the Diamondbacks, but more recently had been working out of the bullpen. He is 2-4 with a 4.15 ERA and one save in 10 total appearances this year.
Left fielder Jason Kubel was held out of the lineup Saturday due to a tight right hamstring. He was removed in the seventh inning of Arizona's 8-1 loss Friday.