Hill was born on December 20, 1983, in Los Angeles, California. His parents are Sharon Lyn , a costume designer and fashion stylist, and Richard Feldstein, a tour accountant for Guns N' Roses. He has a younger sister, actress Beanie Feldstein (b. 1993). Their older brother, Jordan Feldstein (1977–2017), was a music manager for Robin Thicke and Maroon 5 until his sudden death at age 40 from a pulmonary embolism. Their parents were originally from Long Island, New York, and the family vacationed in the Catskill Mountains.
Hill and his siblings were raised in the wealthy Los Angeles neighborhood of Cheviot Hills, where he continues to reside, and attended the Center for Early Education, Brentwood School, and then Crossroads School in Santa Monica. He worked at Hot Rod Skateboard Shop on Westwood Boulevard in Los Angeles. After graduating from high school in 2002, he attended The New School, Bard College and the University of Colorado Boulder, but did not earn a degree.
Hill is Jewish and had a bar mitzvah ceremony.
