A system that safely executes a native code module on a computing device. During operation, the system receives the native code module, which is comprised of untrusted native program code expressed using native instructions in the instruction set architecture associated with the computing device. The system then loads the native code module into a secure runtime environment, and proceeds to execute a set of instructions from the native code module in the secure runtime environment. The secure runtime environment enforces code integrity, control flow integrity, and data integrity for the native code module. Furthermore, the secure runtime environment moderates which resources can be accessed by the native code module on the computing device and/or how these resources can be accessed. By executing the native code module in the secure runtime environment, the system facilitates achieving native code performance for untrusted program code without a significant risk of unwanted side effects.