The Rangers selected Collyer's contract from Triple-A Round Rock on Wednesday, Kennedi Landry of MLB.com reports.
Collyer will come up from the minors to help fill the holes in Texas' bullpen left by Chris Martin (biceps) and Luis Curvelo (shoulder). The 24-year-old Collyer has started the Triple-A season strong, giving up just two runs over 6.2 innings while striking out 11 batters and walking two. He'll be making his MLB debut whenever he gets into a game.