Teen star McKenzie Phillips busted for drugs.

Phillips, the former One Day at a Time star, was arrested at LAX airport for possession of heroin and coaine.

Cops were summoned to Terminal 4 where Phillips was being screened by security. 

She is currently in police custody after bags believed to contain heroin and coke were discovered.

McKenzie, the daughter of The Mammas and the Papas lead singer John Phillips and first wife Susan Adams and the stepchild of singer/actress Michelle Phillips, has a long history of drug abuse. 

Her first major acting role was in  George Lucas' seminal American Graffiti (1973) and then shot to TV fame as Bonnie Franklin's daughter on sitcom One Day at a Time in the 1970s.