State-of-the-art automatic reliability analyses as used in system-level design approaches mainly rely on Binary Decision Diagrams (BDDs) and, thus, face two serious problems: (1) The BDDs exhaust available memory during their construction and/or (2) the final size of the BDDs is, sometimes up to several orders of magnitude, larger than the available memory. The contribution of this paper is twofold: (1) A partitioning-based early quantification technique is presented that aims to keep the size of the BDDs during construction at minimum. (2) A SAT-assisted simulation approach aims to deliver approximated results when exact analysis techniques fail because the final BDDs exhaust available memory. The ability of both methods to accurately analyze larger and more complex systems than known approaches is demonstrated for various test cases. Categories and Subject Descriptors C.4 [Performance of Systems]: Reliability, availability, and serviceability General Terms Reliability, design Key...