We describe the implementation of EMX, a commercial full-wave 3D Electromagnetic simulator used for Integrated Circuit (IC) design. EMX uses a volume integral equation formulation and a specialized iterative solver that is accelerated using a new 3D kernel independent Fast Multipole Method. The code has been implemented to take advantage of multiple-core machines. In addition, domain specific implementation issues are discussed. For example, in advanced IC processes, the physical properties of wires vary depending on the surrounding wiring. EMX automatically modifies the drawn layout to mimic the IC fabrication process. We compare simulation results to measurements over a large variety of IC structures.