The rapid layout synthesis of a microresonator from high-level functional specifications and design constraints is demonstrated. Functional parameters such as resonant frequency, quality factor, and displacement amplitude at resonance are satisfied while simultaneously minimizing an objective function. The optimal synthesis tool allows exploration of micromechanical design issues and objectives, as illustrated with a polysilicon lateral resonator example modeled in three mechanical degrees-of-freedom. Layouts for three sets of five different resonators from 3 kHz to 300 kHz are generated, with each set globally optimized to minimize either active device area, electrostatic drive voltage, or a weighted combination of area and drive voltage.