After surviving the Holocaust, Librescu was repatriated to Communist Romania. He studied aerospace engineering at the Polytechnic University of Bucharest, graduating in 1952 and continuing with a Master's degree at the same university. He was awarded a Ph.D. in fluid mechanics in 1969 at the Academia de Științe din România. From 1953 to 1975, he worked as a researcher at the Bucharest Institute of Applied Mechanics, and later at the Institute of Fluid Mechanics and the Institute of Fluid Mechanics and Aerospace Constructions of the Academy of Science of Romania.