Hardy was placed on the DL on April 13 with a strained left oblique. He was in the starting lineup for Tuesday night's game against the Seattle Mariners.
Obtained during the offseason in a trade with Minnesota, Hardy hit .200 in his first six games with Baltimore before the injury.
Rupe had a 5.65 ERA in nine games with Baltimore. Manager Buck Showalter expressed hope that the right-hander would pass through waivers and accept an assignment with Triple-A Norfolk.
Signed as a minor-league free agent in November, Rupe lives in Virginia Beach.