This paper presents SAM (Software Architecture Modeling and Analysis), a set of tools that capture the workload model, performance objectives, and helps the architect to identify an appropriate architecture of a software intensive system. To begin with, the architect captures the AS-IS architecture with performance constraints. This is assessed by building a Layered Queuing Network (LQN) and solved using Discrete Event Simulation (DES). The tool then allows the architects to apply a set of architectural tactics and reassess the architecture. This helps the architect to perform a series of successive refinements iteratively and eventually move towards an appropriate architecture that meets the performance objectives.