Tim McGraw Honors Glen Campbell With Moving Oscars Performance

The ailing legend's family chose McGraw to fill in for him on the nominated song "I'm Not Gonna Miss You"

The Oscars took a solemn turn when Tim McGraw took the stage Sunday night. Dressed in a tuxedo and his signature black cowboy hat, the country superstar sang Glen Campbell's nominated song, "I'm Not Gonna Miss You," sitting on a stool without his guitar — or anything else to detract from the emotional lyrics penned by Campbell with Julian Raymond as a love letter to his family.

McGraw was handpicked by the Campbell family to fill in for the ailing legend. A first-time Oscar nominee, Campbell was unable to travel to Los Angeles for the show due to his deteriorating health. The 78-year-old "Rhinestone Cowboy" was diagnosed with Alzheimer's disease in 2011 and had to be moved into a memory care facility last year. Raymond tells Rolling Stone Country that, sadly, Campbell doesn't understand their nomination.

"I was so pleased that the Grammys gave him a Lifetime Achievement award when he could still understand what it was and appreciate it. But this is a whole different deal," says the pop-country icon's producer and co-writer. "It's a cliché thing to say, but I'm just so happy to be nominated, for him and his family. I feel just so happy that this whole thing is creating a brand-new legacy for him and getting some of those great old songs heard. As we joke, he's lived a thousand lifetimes. He's just amazing in so many ways."

Penned during the earlier stages of Campbell's illness, "I'm Not Gonna Miss You" is the final song of the legendary entertainer's 60-year career, written and recorded for his 2014 documentary, Glen Campbell…I'll Be Me. The bittersweet love song sends the poignant message that the silver lining of Alzheimer's is that he won't feel his loved ones' pain as they watch him succumb to the disease. His wife, Kim Campbell, tells Rolling Stone Country that making music acted as a speed bump in the early progression of his Alzheimer's.

"Music utilizes all of the brain, not just one little section of it," she says. "Everything's firing all at once. It's really stimulating and probably helped him plateau and not progress as quickly as he might have. I could tell from his spirits that it was good for him. It made him really happy. It was good for the whole family to continue touring and to just keep living our lives. And we hope it encourages other people to do the same."

Kim and daughter Ashley Campbell attended the Academy Awards, stopping to pose with McGraw and wife Faith Hill on the red carpet. "I'm Not Gonna Miss You" was nominated alongside songs from Selma, The Lego Movie, Beyond the Lights and Begin Again. Selma's "Glory," written and performed by John Legend and Common, was the winner.

Click here for Rolling Stone's complete coverage of the 87th annual Academy Awards, and scroll below to see exclusive behind-the-scenes photos, courtesy of Tim McGraw.