Abstract: A computer-based system and method automate the generation of megacells in the design and layout of integrated circuits. The preferred method utilizes an automatic design generator having a user interface which receives design requirements for a megacell or other complex integrated circuit design. A megacell processor receives the design requirements for the megacell and retrieves relevant megacell implementations from a megacell library. Stored megacell benchmarks are then retrieved from a megacell benchmark memory and applied to corresponding megacells to determine which of the various implementations optimally satisfies the user design requirements. Once the optimal megacell implementation is selected, the megacell processor produces a logic design consisting of a net list and a physical design consisting of design directives which are then used to place and route the megacell as a finished layout.