Zach Sobiech is a 17-year-old musician who was diagnosed three years ago with osteosarcoma, a rare form of bone cancer. With only months to live, Sobiech used music to say goodbye — moving millions of people with his song, "Clouds."

Media company SoulPancake is helping spread Sobiech's message with a tribute video, featuring a superstar list of celebrities, including Bryan Cranston, Sarah Silverman, Andy Grammer, Colbie Caillat, Jason Mraz, Sara Bareilles, The Lumineers and many more.

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Sobiech's version is available on iTunes, and proceeds benefit the Children's Cancer Research Fund.

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