The 28-year-old Aussie, who plays murdered actress Sharon Tate, shared a photo from the set and show her dressed in a classic 60s monochrome look with black turtle neck and white mini skirt and boots.
'First look. #OnceUponATimeInHollywood @onceinhollywood' Margot captioned the pic.
Sharon Tate was married to director Roman Polanski but was murdered by Charles Manson and members of the Manson family in 1969 when she was eight-and-a-half months pregnant with her first child.
The film also stars Leonardo DiCaprio and Brad Pitt who respectively play a "former star of a western TV series, and his longtime stunt double," Deadline quoted Quentin as saying.
"Both are struggling to make it in a Hollywood they don’t recognise anymore. But [DiCaprio's character] Rick has a very famous next-door neighbour…Sharon Tate."
The film is scheduled for release on August 9, 2019, in line with the 50th anniversary of Tate’s murder.