Barnes spent the 2014 season in the Indians' organization, pitching for Triple-A Columbus. He went 3-2 with a 3.69 ERA in 25 games.
Guilmet, a right-hander, appeared in 10 games for the Orioles in '14, allowing six earned runs in 10 1/3 innings.
William Boor is a reporter for MLB.com. Follow him on Twitter at @wboor. This story was not subject to the approval of Major League Baseball or its clubs.