Smith (shoulder) signed a minor-league contract with the Red Sox on Sunday, Brandon Warne of ZoneCoverage.com reports.
Smith elected to become a free agent at the beginning of November, although he'll return to Boston on this farm deal. He posted a 3.77 ERA and 1.40 WHIP with 18 strikeouts across 14.1 frames as a reliever in 2018 and could make his way back to the big leagues if he performs well in spring training.