Abstract: Understanding the fate of merging supermassive black holes in galactic mergers, and the gravitational wave emission from this this process, are two important LISA science goals. These are not only expected to provide one the most extreme tests of general relativity in the strong field spacetime dynamics, but the final spin, recoil velocity of the remnant black hole may provide an observational probe for the growth history of supermassive black holes at the core of galaxies. To this end, we review the present status of numerical relativity simulations of binary black hole mergers with a particular emphasis on the Lazarus method for modeling these events.