Glen Campbell was one of country music's first true crossover superstars. Now a documentary about his farewell tour is coming to a limited theatrical run.

Director James Keach and his film crew followed Campbell on his Goodbye Tour, which the singer-guitarist announced after being diagnosed with advanced Alzheimer's in 2011. The film documents his life onstage and off during the tour, during which he sometimes visibly struggled with the music he had performed for his entire adult life.

Since the tour wrapped, Campbell has been moved to a full-time care facility, and his wife has revealed that it is unlikely he will ever perform publicly again.

The 78-year-old music legend began his career as a top session player in the Los Angeles pop scene, playing on recordings by the Beach Boys, Elvis Presley, Frank Sinatra, Simon & Garfunkel and many more.

After a stint replacing Brian Wilson in the Beach Boys' live shows, he went on to an enormously successful run of solo hits that included 'Gentle on My Mind,' 'By the Time I Get to Phoenix,' 'Wichita Lineman' and the career-defining 'Rhinestone Cowboy.' He also hosted a variety show, 'The Glen Campbell Goodtime Hour,' on CBS for four seasons.

'I'll Be Me' features commentary from fellow musicians Blake Shelton, Sheryl Crow, Keith Urban, Brad Paisley, Taylor Swift and Vince Gill, as well as friends and fans like Steve Martin, Bruce Springsteen, U2's the Edge, Paul McCartney, Jimmy Webb, Jay Leno and Bill Clinton. After premiering at the Nashville Film Festival in April, it is set to open in a limited theatrical release in New York and Nashville on Oct. 24.