Holmes was recalled from Triple-A Indianapolis on Monday, Bill Brink of the Pittsburgh Post-Gazette reports.
He'll take the 25-man roster spot of Joe Musgrove (shoulder), who was placed on the 10-day disabled list. Holmes previously joined the Pirates as the 26th man for their Sunday doubleheader against the Tigers but didn't get the opportunity to make his major-league debut. Musgrove's stay on the DL could be short, but Holmes should at least receive his first MLB action at some point this week. If he doesn't receive Musgrove's previously scheduled start Thursday against the Reds, Holmes will likely work in long relief. Bullpen arms Steven Brault and Tyler Glasnow are more likely candidates to move into the rotation on a short-term basis while Musgrove is sidelined.