Tied 2-2 entering the frame, Wells connected on a solo shot off Jason Berken (0-1) to gave Toronto the lead, and Overbay followed with a 2-run shot -- his second homer of the game -- off Alberto Castillo to ice the victory for the Blue Jays, their fourth in six games.
Aaron Hill also socked a home run for Toronto, which broke a team record for most round-trippers in a month. With Saturday's three blasts, the Blue Jays have hit 50 in May.
Brett Cecil (5-2) collected the win, limiting the O's to two runs on four hits over eight innings, walking none and striking out seven. Cecil has allowed only six hits in 15 1/3 innings over his last two starts, posting his third straight win.
Nick Markakis went 2-for-4 with an RBI in Baltimore's loss.