A new documentary called Twenty Feet From Stardom tells the story of backup singers.  The film profiles women who have sang with some of the world's biggest stars.  Darlene Love, Merry Clayton, Claudia Lennear, Lisa Fischer, and Judith Hill have sang with artists like The Rolling Stones, Lynyrd Skynyrd, Bruce Springsteen, Sting, Stevie Wonder, Ray Charles, and more.

Clayton talked about her career and the film with CBS Sunday Morning.  She's sang with many of the best.  But, she is best known for her duet with Mick Jagger on the Rolling Stones classic Gimme Shelter.

She says she got the call late one night.  Clayton recalls, "I said, who are these guys who wants somebody to get up out of their warm bed, pregnant, and come sing with them?"

Clayton said that she believed that many classic rock bands wanted strong, black women singing because, "we are the choir."  But, the lyrics for Gimme Shelter aren't very choir-like.  She says, I could not believe, I said, 'What is this? 'Rape, murder, it's just a shot away?'"

Listen to the isolated vocal track to the song, below.  It's powerful.

Another notable song that Clayton contributed to was Lynyrd Skynyrd's Sweet Home Alabama.  She didn't want to do it.  Listen to her tell the story below.

Watch the trailer to Twenty Feet From Stardom.