The White Sox optioned right-hander Zach Stewart to AAA Charlotte and recalled right-hander Dylan Axelrod on Tuesday.
Axelrod, 26, has a 5-4 record and 3.18 ERA over 68 innings for the Knights. He struck out 66 in 11 starts. Axelrod was with the Sox from April 27-May 5, going 0-1 with a 3.52 ERA in three appearances including one start.
He will assume Stewart's role as the long relief man and possibly an occasional starter, manager Robin Ventura said.
"He'll be the long guy, be in the bullpen,'' Ventura said. "For right now, that's where he'll be. Maybe a little bit down the road if something else happens he might be able to spot-start on occasion.''
Stewart made his first start of the season and was roughed up for four homers in the Sox' 12-3 loss to the Cubs on Monday.
Stewart is 1-2 with a 6.00 ERA in 18 games this season.