Mejia was claimed by the Cardinals on Tuesday.
Mejia will be added to the big-league roster after being picked up by the Cardinals. He owns an ugly 7.32 ERA and 1.68 WHIP with a 21:13 K:BB over 19.2 innings and was designated for assignment by the Angels on Friday, though St. Louis is hopeful a change in scenery is just what the lefty needs to get back on track.