Saunders went 0 for 4 in his return to the lineup Saturday after sitting out the previous four games. Saunders underwent knee surgery in spring training to repair a torn meniscus and didn't make his debut until April 25. He had a cortisone shot and had fluid drained from his knee Monday.
A seven-year veteran who previously played for Seattle, Saunders is batting .194 with no homers and three RBIs.
Tolleson joins the Blue Jays for the second time this season. He appeared in seven games in April, batting .200 with no homers and two RBIs.
To make room for Tolleson, the Blue Jays designated minor league right-hander Preston Guilmet for assignment Sunday.