Though Timlin has struggled mightily this season, the Red Sox could use a fresh arm considering the way the bullpen has been roughed up in the first five games of this 10-game road trip.
Timlin had been out since June 17 with left knee tendinitis. In three rehab outings at Triple-A Pawtucket, he didn't give up a hit.
The Red Sox hope that is a sign of things to come. Timlin is 3-3 with a 7.06 ERA in 24 outings this season.
In order to make room for Timlin on the roster, the Sox will option right-hander Chris Smith to Pawtucket. Smith went 1-0 with a 2.84 ERA in three outings for Boston.
Ian Browne is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.