McGraw shared the sad news on Twitter today, noting the man the family called "G Pa" "was the sweetest, kindest, most gentle man" he's ever known.
"No man in my life has ever made such an impact on me as to how to be a human, a father and a friend," wrote McGraw.
"I'll never, in 10 lifetimes, be able to live up to his example, but man, he has set a mark that all of us should strive for," he added.
Hill's mother, Edna, died in 2016.
"I actually had a pretty amazing childhood," the 51-year-old country singer once said of her upbringing with the Perry family. "I was adopted…but my family, my mom and my dad and my brothers, they are amazing, very stable, good Christian, God-fearing home, and a great small town of Star, Mississippi. I actually had a really stable childhood."
McGraw, 51, said on social media that "a day will not pass" for the rest of his life that Hill's father won't be in his thoughts.
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