Hjelle was optioned to Triple-A Sacramento on Saturday, Evan Webeck of The San Jose Mercury News reports.
Hjelle was recalled Wednesday and tossed four innings as the bulk reliever against the Rockies, picking up a win. His regular season may be done, though the Giants could still recall him if another player hits the injured list in a corresponding move. If he doesn't pitch in the big leagues against this season, he'll end his rookie campaign with a 7.20 ERA in 20 innings of relief.