Software development is a dynamic process where engineers constantly modify and refine their systems. As a consequence, everything evolves including designs, system's architectural structure, and implementation source code. This paper contributes a novel approach to manage architectural evolution of software systems at the logical level. Key to Molhado architectural software configuration management (SCM) system is its architectural system model in which the architectural concepts are integrated into the system model to enable the management of unplanned evolution of software architecture. Via our product versioning SCM approach, consistent configurations are maintained not only among source code but also with the high-level software architecture. Molhado's architectural system model can also be extended to support different architectural description languages and architectural styles.