In late 2012, Simon was diagnosed with terminal colorectal cancer which later metastasized to his other organs, including his liver and kidneys. He had been feeling ill for some time and was frequently misdiagnosed with various viruses. He was given between three to six months to live; chemotherapy treatment reduced the size of his tumors over the following six months. He arranged for his fortune to be left to various charitable causes, stating "The truth is, I have more money than I'm interested in spending. Everyone in my family is taken care of. And I enjoy this." Simon died in his Los Angeles home from complications from the disease on March 8, 2015.