The Pirates selected Murdock's contract and optioned him to Triple-A Indianapolis on Sunday, Alex Stumpf of MLB.com reports.
Murdock will be added to the 40-man roster after he exercised an upward-mobility clause in his minor-league contract that would have allowed him to test free agency had the Pirates not cleared a spot for him. The 27-year-old pitched at Single-A Bradenton and Double-A Altoona to begin the season before moving up to Triple-A in early June. Over the past month, Murdock has submitted a 4.26 ERA, 1.26 WHIP and 21:4 K:BB in 12.2 innings out of the Indianapolis bullpen.