Hillier Architecture, Princeton, N.J., is set to be acquired by RMJM, a London-based architecture firm with 700 employees and 11 international offices in Europe, Asia and the Middle East, say industry sources. RMJM has projects in about 15 countries in a wide range of industry sectors, including education, commercial, industrial, residential, research and development, health care and public buildings. The companies did not confirm the transaction. The deal will be announced on June 19 in New York City.