The famous sing the praises of the not-so-famous in “20 Feet From Stardom.”

Bruce Springsteen, Stevie Wonder, Mick Jagger, Chris Botti, Patti Austin and Sting are all part of the choir. They express their informed appreciation of the invaluable contributions that Darlene Love, New Orleans native Merry Clayton, Judith Hill, Claudia Lennear, Lisa Fischer, Táta Vega, the Waters siblings and other normally unheralded backup singers have made to music.

“20 Feet From Stardom” does for supporting vocalists what “Standing in the Shadows of Motown” did for recording session instrumentalists. In the latter 2002 concert-documentary, musicians who played for the many dozens of hits released by Motown Records moved briefly into the spotlight.

“20 Feet From Stardom,” directed by Morgan Neville (“Respect Yourself: The Stax Records Story,” “Hank Williams: Honky Tonk Blues”), casts belated attention upon singers who enlivened recordings by Phil Spector, Carole King, the Rolling Stones, Lou Reed, Talking Heads, Joe Cocker, Michael Jackson and many others.

“There’s a power to what we do,” Janice Pendarvis (David Bowie, Steely Dan, Peter Tosh, Jimmy Cliff, the Stones) tells Neville’s camera. “No one till now has publicly acknowledged it.”

The documentary’s stories, told by the singers themselves, music executive and producer Lou Adler and the aforementioned stars, can be heartbreaking. Adler and others express their dismay and disbelief that singers they admired so much did not become stars themselves. Fischer even won a Grammy in 1992 but subsequently slipped back into her backup singing career.

The soul and vocal blend that backup singers graced recordings and performances with can often be traced to the church. Love and Clayton, to name a few, had minister fathers.

As a child in Gert Town, Clayton sang in choirs at Mount Moriah Baptist Church from the age of 4. She continued singing after her family moved to Los Angeles when she was 8. It was there that Clayton went to school with Darlene Love’s sister, Edna, and soon joined the ranks of L.A.’s most coveted session vocalists.

“20 Feet From Stardom” also features a great collection of vintage film footage. Spector and Love are seen in the studio, for instance, and there’s performance video of Ray Charles with his Raelettes and Ike and Tina Turner with the Ikettes. Along with the classic footage, stylishly shot contemporary scenes of the singers and their celebrity fans bring the film’s subjects full circle. Clayton stars in an especially compelling scene featuring her return to the studio where she sang a midnight session for the Rolling Stones’ “Gimmie Shelter.” Let the record show, she nailed it.

Clayton, Love, Fischer, Vega and other talents share their deep disappointments and frustrations, but they’re all, as “20 Feet From Stardom” reveals in such a classy, moving way, survivors.