The Cubs claimed Aguiar off waivers from the Reds on Saturday, C. Trent Rosecrans of The Athletic reports.
Aguiar was pushed off the Reds' 40-man roster after giving up two earned runs in three innings with Cincinnati and posting a 6.27 ERA at Triple-A, but he'll reclaim a roster spot upon joining his new organization. The 25-year-old won't be eligible to pitch for Chicago in the postseason, but he could be recalled to help preserve the team's bullpen during the final weekend of the regular season.