The right-hander went 3-6 with a 2.49 ERA in 68 appearances for the Minnesota Twins last season.
Boyer, 34, is 12-21 with a 4.22 career ERA over parts of nine major-league seasons. He has pitched for six different clubs.
He retired after the 2011 season and returned two years later. He pitched for the San Diego Padres in 2014 before joining the Twins last season.