Cust, 32, hit .213 with three home runs and 23 RBIs in 225 at-bats this season with the Seattle Mariners, who released him last week. He is a left-handed hitter that could help the Phillies in September and possibly beyond, if they like what they see in Lehigh Valley.
"He's a power bat," Phillies general manager Ruben Amaro Jr. said. "We don't have a ton of power off the bench right now. We don't have a guy that is that kind of a threat, so we thought it was worth a shot to see what he's got."