The Twins made the move made before the start of a three-game series against Cleveland. Michael Tonkin was recalled from Triple-A Rochester to take Boyer's place in the bullpen.
Boyer has been a find for the Twins this year. The right-hander was brought to spring training as a nonroster invitee after pitching last season for San Diego. He has a 2.98 ERA in 51 appearances over 48 1/3 innings with 15 walks and 25 strikeouts.
Tonkin already has had three stints with the Twins this season. He has a 5.73 ERA in 16 appearances over 11 innings with five walks and 10 strikeouts.