Grilli had been on the DL since Aug. 2 with right elbow inflammation. He pitched one hitless inning in rehab with Double-A Frisco on Thursday before rejoining the club.
Since coming over via trade from the Colorado Rockies on June 9 in exchange for cash considerations, Grilli has posted a 1.53 ERA in 17 2/3 innings.
Eyre had a 3.48 ERA in eight relief outings over four different stints with the Rangers this season.
Lisa Winston is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.