The Dodgers recalled Halvorsen from Triple-A Oklahoma City on Thursday.
Halvorsen will replace Roki Sasaki (finger) on the active roster and replenish the Dodgers' bullpen depth as Eric Lauer moves back into the rotation. Halvorsen owns a 4.50 ERA and 1.90 WHIP across 20 innings this season but has yet to give up a run in the majors or at Triple-A since joining the Dodgers organization in late July.