In return, Chicago sent minor league right-hander Thomas Hatch to Toronto. The Cubs also transferred left-hander Xavier Cedeno to the 60-day injured list to make room for Phelps on the 40-man roster.
Phelps, 32, has a 3.63 ERA and a 1.21 WHIP in 17 appearances this season. He has struck out 9.3 batters per nine innings and has held foes to a .222 batting average.
Pehlps missed the 2018 seasona and the early part of 2019 while recovering from Tommy John surgery. He has a career 3.88 ERA.
Hatch, 24, has a 4.59 ERA and 1.41 WHIP in 21 starts at Double-A Tennessee. The Cubs selected him in the third round of the 2016 amateur draft.