Margot Robbie is now officially in negotiations to play murdered Sharon Tate in Quentin Tarantino's star-studded Once Upon a Time in Hollywood.

Tarantino reportedly met with Robbie to discuss the role last summer (17), but he never officially offered her the job - until now.

According to Deadline sources, the I, Tonya Oscar nominee has the offer and negotiations are underway.

If she signs on, she'll join a cast that already features her Wolf of Wall Street co-star Leonardo DiCaprio and Brad Pitt.

Tarantino's new film - his first for Sony Pictures - will take fans back to 1969 Los Angeles, as Charles Manson's cult members plan a killing spree that was to include the slaughter of Roman Polanski's pregnant wife Tate.

DiCaprio will play Rick Dalton, an ageing a western TV star, and Pitt is set to portray his longtime stunt double, Cliff Booth.

DiCaprio's character just happens to live next door to actress Tate.

Tarantino's film has come under fire from Tate's sister Debra, who has accused the director of exploiting the tragic star and the 50th anniversary of her death next year (19).

Sharon's furious sibling has also taken aim at actress Hilary Duff's "tasteless" upcoming independent horror movie The Haunting of Sharon Tate, which follows the late model in the days leading up to her murder, with the story angle leaning toward the star being haunted by ghosts in the final weeks of her life.

But Debra has approved Kate Bosworth's forthcoming depiction of her sister in an upcoming film directed by the Still Alice star's husband Michael Polish, and is so excited about the movie, she even signed on as a co-producer.

"At long last I have found filmmakers who are interested in the life story of my sister Sharon," Debra wrote in a statement last week (07Mar18). "Other projects have been a real source of pain in their insensitivity and gross exploitation of my sister."