diff --git a/compiler-rt/lib/scudo/standalone/CMakeLists.txt b/compiler-rt/lib/scudo/standalone/CMakeLists.txt
--- a/compiler-rt/lib/scudo/standalone/CMakeLists.txt
+++ b/compiler-rt/lib/scudo/standalone/CMakeLists.txt
@@ -10,6 +10,9 @@
   -g
   -nostdinc++)
 
+# Too many existing bugs, needs cleanup.
+append_list_if(COMPILER_RT_HAS_WNO_FORMAT -Wno-format SCUDO_CFLAGS)
+
 # Remove -stdlib= which is unused when passing -nostdinc++.
 string(REGEX REPLACE "-stdlib=[a-zA-Z+]*" "" CMAKE_CXX_FLAGS ${CMAKE_CXX_FLAGS})
 
diff --git a/compiler-rt/lib/scudo/standalone/string_utils.h b/compiler-rt/lib/scudo/standalone/string_utils.h
--- a/compiler-rt/lib/scudo/standalone/string_utils.h
+++ b/compiler-rt/lib/scudo/standalone/string_utils.h
@@ -26,15 +26,16 @@
     String.push_back('\0');
   }
   void append(const char *Format, va_list Args);
-  void append(const char *Format, ...);
+  void append(const char *Format, ...) FORMAT(2, 3);
   void output() const { outputRaw(String.data()); }
 
 private:
   Vector<char> String;
 };
 
-int formatString(char *Buffer, uptr BufferLength, const char *Format, ...);
-void Printf(const char *Format, ...);
+int formatString(char *Buffer, uptr BufferLength, const char *Format, ...)
+    FORMAT(3, 4);
+void Printf(const char *Format, ...) FORMAT(1, 2);
 
 } // namespace scudo
 
diff --git a/compiler-rt/lib/scudo/standalone/string_utils.cpp b/compiler-rt/lib/scudo/standalone/string_utils.cpp
--- a/compiler-rt/lib/scudo/standalone/string_utils.cpp
+++ b/compiler-rt/lib/scudo/standalone/string_utils.cpp
@@ -236,7 +236,6 @@
   va_end(ArgsCopy);
 }
 
-FORMAT(2, 3)
 void ScopedString::append(const char *Format, ...) {
   va_list Args;
   va_start(Args, Format);
@@ -244,7 +243,6 @@
   va_end(Args);
 }
 
-FORMAT(1, 2)
 void Printf(const char *Format, ...) {
   va_list Args;
   va_start(Args, Format);