The Giants reinstated Miller (back) from the injured list Saturday.
Miller will return to the Giants' bullpen after making just two rehab appearances in the minors, during which he gave up two hits and struck out three batters over two innings. The 28-year-old southpaw owns a 3.18 ERA and 1.24 WHIP through 11.1 innings in the big leagues this year and is likely to compete with Caleb Kilian for saves immediately after returning from the IL. Tristan Beck was optioned to Triple-A in a corresponding move.