Memory/Address Sanitizer vs Valgrind

I think you'll find this wiki useful.

TLDR main advantages of sanitizers are

• much smaller CPU overheads (Lsan is practically free, UBsan is 1.25x, Asan and Msan are 2-4x for computationally intensive tasks and 1.05-1.1x for GUIs, Tsan is 5-15x)
• wider class of detected errors (stack and global overflows, use-after-return)
• full support of multi-threaded apps (Valgrind support for multi-threading is a joke)
• much smaller memory overhead (up to 2x for Asan, up to 3x for Msan, up to 10x for Tsan which is way better than Valgrind)

Disadvantages are

• more complicated integration (you need to teach your build system to understand Asan and sometimes work around limitations/bugs in Asan itself, you also need to use relatively recent compiler)
• MemorySanitizer is not reall^W easily usable at the moment as it requires one to rebuild all dependencies under Msan (including all standard libraries e.g. libc++); this means that casual users can only use Valgrind for detecting uninitialized errors
• sanitizers typically can not be combined with each other (the only supported combination is Asan+UBsan+Lsan) which means that you'll have to do separate QA runs to catch all types of bugs

One big difference is that the LLVM-included memory and thread sanitizers implicitly map huge swathes of address space (e.g., by calling mmap(X, Y, 0, MAP_NORESERVE|MAP_ANONYMOUS|MAP_FIXED|MAP_PRIVATE, -1, 0) across terabytes of address space in the x86_64 environment). Even though they don't necessarily allocate that memory, the mapping can play havoc with restrictive environments (e.g., ones with reasonable settings for ulimit values).