The Cubs have designated righty Donn Roach for assignment, the club announced (via Mark Gonzales of the Chicago Tribune, on Twitter). His 40-man spot was needed for the activation of Mike Olt from the DL. Olt was optioned to Triple-A.
Roach, 25, gave up four earned runs in a 3 1/3 inning appearance at the major league level. He has thrown 89 innings with a healthy 2.33 ERA at the Triple-A level on the year, striking out 3.3 and walking 1.6 batters per nine in the process.