test/CodeGen/builtin-memfns.c

// RUN: clang -emit-llvm -o - %s | not grep __builtin

int main(int argc, char **argv) {
  unsigned char a = 0x11223344;
  unsigned char b = 0x11223344;
  __builtin_bzero(&a, sizeof(a));
  __builtin_memset(&a, 0, sizeof(a));
  __builtin_memcpy(&a, &b, sizeof(a));
  __builtin_memmove(&a, &b, sizeof(a));
  return 0;
}