Riefenhauser was claimed off waivers by the Cubs on Friday.
The 26-year-old performed well at Triple-A Durham in 2015, producing a 2.86 ERA in 34.2 innings of work. However, Riefenhauser has a career 6.30 ERA in the major leagues while tossing 20 innings between 2014 and 2015. The Cubs already have a solid bullpen in place, meaning if Riefenhauser stays with the club he will likely begin the season in the minor leagues.