The person spoke on condition of anonymity Wednesday because the deal is pending on Benoit passing a physical.
In his first season as Tigers closer, Benoit had 24 saves in 26 chances. But in Game 2 of the AL championship series, he allowed a tying grand slam by Boston's David Ortiz that was a turning point in the series.
Benoit, who turns 37 on July 26, is expected to replace setup man Luke Gregerson, who was traded to Oakland for outfielder Seth Smith. He could also be insurance for closer Huston Street, who's been on the disabled list three times the last two seasons.