Bostick left Wednesday's practice session due to an ankle injury, Todd Archer of ESPN.com reports.
Bostick played 60 snaps (55 on offense, five on special teams) in Sunday's preseason game against the Rams, which was second most on the Cowboys behind quarterback Trey Lance. Bostick is competing for a depth spot on Dallas' offensive line, and missing time due to injury would hurt his chance at making the 53-man roster.