The Giants activated Hjelle (elbow) from the 15-day injured list Saturday, Alex Pavlovic of NBC Sports Bay Area reports.
Hjelle has shown steady improvement during his rehab assignment, and in his last outing with Triple-A Sacramento on April 17, he struck out two while allowing one hit over one scoreless inning. The right-hander will return to the Giants' bullpen and figures to step into a low-leverage relief role. San Francisco optioned Kai-Wei Teng to Triple-A Sacramento in a corresponding move.