In this paper, we present a point-to-point (P2P) communication synthesis methodology for System-On-Chip (SOC) design. We consider real-time systems where IP selection, mapping and task scheduling are already fixed. Our algorithm takes the communication task graph (CTG) and IP sizes as inputs and automatically synthesizes a P2P communication network, which satisfies the specified deadlines of the application. As main contribution, we first formulate the problem of automatic bitwidth synthesis which minimizes total wirelength and then propose an efficient heuristic to solve it. A key element in our approach is a communication-driven floorplanner which considers the communication energy consumption in the objective function. Experimental results show that, compared to standard shared bus architecture, significant power savings can be achieved by using the P2P scheme and communication-driven floorplanning. For instance, for an H.263 encoder, we estimate 21.6% savings in energy and 15.1% in terms of wiring resources with an area overhead of only 4%.