diff --git a/compiler-rt/lib/sanitizer_common/CMakeLists.txt b/compiler-rt/lib/sanitizer_common/CMakeLists.txt
--- a/compiler-rt/lib/sanitizer_common/CMakeLists.txt
+++ b/compiler-rt/lib/sanitizer_common/CMakeLists.txt
@@ -202,9 +202,6 @@
 
 set(SANITIZER_CFLAGS ${SANITIZER_COMMON_CFLAGS})
 
-# Too many existing bugs, needs cleanup.
-append_list_if(COMPILER_RT_HAS_WNO_FORMAT -Wno-format SANITIZER_CFLAGS)
-
 append_rtti_flag(OFF SANITIZER_CFLAGS)
 
 append_list_if(SANITIZER_LIMIT_FRAME_SIZE -Wframe-larger-than=570
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_internal_defs.h b/compiler-rt/lib/sanitizer_common/sanitizer_internal_defs.h
--- a/compiler-rt/lib/sanitizer_common/sanitizer_internal_defs.h
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_internal_defs.h
@@ -230,19 +230,27 @@
 // Please only use the ALIGNED macro before the type.
 // Using ALIGNED after the variable declaration is not portable!
 # define ALIGNED(x) __attribute__((aligned(x)))
-# define FORMAT(f, a)  __attribute__((format(printf, f, a)))
-# define NOINLINE __attribute__((noinline))
-# define NORETURN  __attribute__((noreturn))
-# define THREADLOCAL   __thread
-# define LIKELY(x)     __builtin_expect(!!(x), 1)
-# define UNLIKELY(x)   __builtin_expect(!!(x), 0)
-# if defined(__i386__) || defined(__x86_64__)
+// Check format strings on 64-bits only because we use %zx to print uptr type,
+// but %zx expects size_t and on 32-bits size_t is defined as 'unsigned int'
+// while we define uptr as 'unsigned long' which causes lots of -Wformat
+// warnings. This can be fixed by defining uptr as 'unsigned int' on 32-bits.
+#  if __LP64__
+#    define FORMAT(f, a) __attribute__((format(printf, f, a)))
+#  else
+#    define FORMAT(f, a)
+#  endif
+#  define NOINLINE __attribute__((noinline))
+#  define NORETURN __attribute__((noreturn))
+#  define THREADLOCAL __thread
+#  define LIKELY(x) __builtin_expect(!!(x), 1)
+#  define UNLIKELY(x) __builtin_expect(!!(x), 0)
+#  if defined(__i386__) || defined(__x86_64__)
 // __builtin_prefetch(x) generates prefetchnt0 on x86
-#  define PREFETCH(x) __asm__("prefetchnta (%0)" : : "r" (x))
-# else
-#  define PREFETCH(x) __builtin_prefetch(x)
-# endif
-# define WARN_UNUSED_RESULT __attribute__((warn_unused_result))
+#    define PREFETCH(x) __asm__("prefetchnta (%0)" : : "r"(x))
+#  else
+#    define PREFETCH(x) __builtin_prefetch(x)
+#  endif
+#  define WARN_UNUSED_RESULT __attribute__((warn_unused_result))
 #endif  // _MSC_VER
 
 #if !defined(_MSC_VER) || defined(__clang__)