General manager Kevin Towers made the announcement Monday prior to Arizona's game at Washington.
This will be Harris' third stint with Arizona this season. He's 0-2 with a 9.24 ERA in 12 relief appearances. In 73 career games with the Diamondbacks, Harris is 4-3 with a 4.13 ERA
The 29-year-old Harris was 3-2 with one save and a 0.99 ERA in 43 games this season with Reno.
Hagens, 25, made his major league debut Aug. 14 at Miami, and went 0-1 with a 3.38 ERA in two relief appearances.