Saunders had surgery on his left knee before the season.
In a freak accident, the Victoria native stepped on a sprinkler head indentation at the Jays' training complex just before the start of sping training.
Saunders has struggled in his recovery from the surgery, batting .194 with six hits and three runs batted in over nine games.
Tolleson played seven games for Toronto this season, batting .200 with three hits and two runs batted in.
Right-hander Preston Guilmet was designated for assignment to make room for Tolleson on the 40-man roster.
The Blue Jays also traded left-handed pitcher Jayson Aquino to the Pittsburgh Pirates in exchange for cash considerations.
The 22-year old Aquino started five games for the class-A Dunedin Blue Jays, posting a 2-2 record with a 2.81 ERA.