Over Valgrind, LLVM developers say that SAFECode in Clang is faster since it doesn't rely upon dynamic binary translation, is more accurate, and provides better error diagnostics with useful information about each memory safety violation.
This current release detects de-references of pointers that are generated from buffer overflows. Additionally, working its way into Clang mainline is support for detecting invalid memory access, invalid calls to free(), usage of un-initalized pointers, memory errors by the misuse of the C standard library functions, and several options.
SAFECode can be activated in Clang by a command-line switch, otherwise this open-source C/C++ compiler works in its normal manner without the memory checking support.
More details can be found in the release announcement of the new Clang with SAFECode.