E. Leroy Tolles, a co-founder of the Los Angeles law firm of Munger, Tolles & Olson, which grew from seven lawyers into a nationally prominent firm with about 200 lawyers, died on Jan. 28 in Palo Alto, Calif. He was 85 and lived in San Marino, Calif., and Montecito, Calif.

The cause was cardiopulmonary failure after a diagnosis of pancreatic cancer, his firm announced.

Mr. Tolles, known as Roy, helped found the firm in 1962 with six colleagues. He spent three decades there, working in a range of fields, including tax law and mining law.

Mr. Tolles was also an investor and partner at Wheeler, Munger & Company, an investment firm. He practiced “value investing,” an investment technique made famous by Warren E. Buffett, and became a wealthy man at a young age, said Charles T. Munger, a fellow founding partner, who is now vice chairman of Berkshire Hathaway, Mr. Buffett’s holding company.

Edwin Leroy Tolles Jr. was born in Winstead, Conn., in 1922 and grew up in Mount Vernon, N.Y. He graduated from Williams College and served as a Marine pilot in the South Pacific in World War II. He received his law degree in 1948 from Harvard.

He is survived by his wife of 63 years, the former Martha Gregory, and four children in California, Stephen, of Pasadena; Roy III, of Piedmont; Thomas, of Santa Monica, and Cynthia Tseng of Palo Alto; and 11 grandchildren. Another son, Henry, died before him.