USC confirmed Davis' departure on Monday. According to Trojans head coach Steve Sarkisian, Davis cited family reasons as his explanation for leaving.
"We wish Bo and his family the best of luck. He is a good coach," Sarkisian said in a statement released by the university. "We will move forward and find a great coach for our defensive line."
Davis previously worked as an assistant under Nick Saban at LSU, the Miami Dolphins and Alabama. The former LSU nose guard coached defensive tackles at Texas from 2011-13, but was not retained on Charlie Strong's staff.
Texas hired Alabama defensive line coach Chris Rumph for the job, so Saban reached out to his longtime assistant with an opportunity to return home.
Steve Sarkisian is now faced with the task of replacing a defensive line coach in time for the home stretch of recruiting for the 2014 class. According to the Los Angeles Times, Sarkisian will reach out to Ed Orgeron, the Trojans defensive line coach under Lane Kiffin and interim coach for the 2013 season after Kiffin's dismissal.