Eflin will have his contract selected before Tuesday's game against Toronto, which he is expected to start.
The Phillies optioned Luis Garcia to Triple-A Lehigh Valley to make room for Eflin. This will be the major league debut for the 22-year-old, and it comes against the Blue Jays, one of the better offenses in the majors this season (3.25 runs per game). Eflin has a 5-2 record with a 2.90 ERA in 11 minor league starts this season.