diff --git a/compiler-rt/cmake/Modules/CompilerRTCompile.cmake b/compiler-rt/cmake/Modules/CompilerRTCompile.cmake
--- a/compiler-rt/cmake/Modules/CompilerRTCompile.cmake
+++ b/compiler-rt/cmake/Modules/CompilerRTCompile.cmake
@@ -24,6 +24,26 @@
   set(${out_flags} "${clang_flags}" PARENT_SCOPE)
 endfunction()
 
+# Add warnings to catch potential errors that can lead to security
+# vulnerabilities.
+function(add_security_warnings out_flags macosx_sdk_version)
+  set(flags "${${out_flags}}" -Werror=builtin-memcpy-chk-size -Werror=format-security
+      -Werror=array-bounds -Werror=uninitialized -Werror=array-bounds-pointer-arithmetic
+      -Werror=shadow -Werror=empty-body -Werror=sizeof-pointer-memaccess
+      -Werror=return-stack-address -Werror=sizeof-array-decay -Werror=sizeof-array-argument
+      -Werror=memset-transposed-args -Werror=format-insufficient-args)
+
+  # Add -Wformat-nonliteral only if we can avoid adding the defintion of
+  # eprintf. On Apple platforms, eprintf is needed only on macosx and only if
+  # its version is older than 10.7.
+  if ("${macosx_sdk_version}" VERSION_GREATER_EQUAL 10.7 OR
+      "${macosx_sdk_version}" EQUAL 0)
+    set(flags "${flags}" -Werror=format-nonliteral -DDONT_DEFINE_EPRINTF)
+  endif()
+
+  set(${out_flags} "${flags}" PARENT_SCOPE)
+endfunction()
+
 # Compile a sanitizer test with a freshly built clang
 # for a given architecture, adding the result to the object list.
 #  - obj_list: output list of objects, populated by path
diff --git a/compiler-rt/cmake/Modules/CompilerRTDarwinUtils.cmake b/compiler-rt/cmake/Modules/CompilerRTDarwinUtils.cmake
--- a/compiler-rt/cmake/Modules/CompilerRTDarwinUtils.cmake
+++ b/compiler-rt/cmake/Modules/CompilerRTDarwinUtils.cmake
@@ -413,6 +413,12 @@
                       ../profile/InstrProfilingInternal.c
                       ../profile/InstrProfilingVersionVar.c)
   foreach (os ${ARGN})
+    set(macosx_sdk_version 0)
+    if ("${os}" STREQUAL "osx")
+      find_darwin_sdk_version(macosx_sdk_version "macosx")
+    endif()
+    add_security_warnings(CFLAGS ${macosx_sdk_version})
+
     list_intersect(DARWIN_BUILTIN_ARCHS DARWIN_${os}_BUILTIN_ARCHS BUILTIN_SUPPORTED_ARCH)
 
     if((arm64 IN_LIST DARWIN_BUILTIN_ARCHS OR arm64e IN_LIST DARWIN_BUILTIN_ARCHS) AND NOT TARGET lse_builtin_symlinks)
diff --git a/compiler-rt/include/profile/InstrProfData.inc b/compiler-rt/include/profile/InstrProfData.inc
--- a/compiler-rt/include/profile/InstrProfData.inc
+++ b/compiler-rt/include/profile/InstrProfData.inc
@@ -129,10 +129,10 @@
 INSTR_PROF_RAW_HEADER(uint64_t, Version, __llvm_profile_get_version())
 INSTR_PROF_RAW_HEADER(uint64_t, BinaryIdsSize, __llvm_write_binary_ids(NULL))
 /* FIXME: A more accurate name is NumData */
-INSTR_PROF_RAW_HEADER(uint64_t, DataSize, DataSize)
+INSTR_PROF_RAW_HEADER(uint64_t, DataSize, DataSizeInitVal)
 INSTR_PROF_RAW_HEADER(uint64_t, PaddingBytesBeforeCounters, PaddingBytesBeforeCounters)
 /* FIXME: A more accurate name is NumCounters */
-INSTR_PROF_RAW_HEADER(uint64_t, CountersSize, CountersSize)
+INSTR_PROF_RAW_HEADER(uint64_t, CountersSize, CountersSizeInitVal)
 INSTR_PROF_RAW_HEADER(uint64_t, PaddingBytesAfterCounters, PaddingBytesAfterCounters)
 INSTR_PROF_RAW_HEADER(uint64_t, NamesSize,  NamesSize)
 INSTR_PROF_RAW_HEADER(uint64_t, CountersDelta,
diff --git a/compiler-rt/lib/builtins/CMakeLists.txt b/compiler-rt/lib/builtins/CMakeLists.txt
--- a/compiler-rt/lib/builtins/CMakeLists.txt
+++ b/compiler-rt/lib/builtins/CMakeLists.txt
@@ -699,6 +699,7 @@
   darwin_add_builtin_libraries(${BUILTIN_SUPPORTED_OS})
 else ()
   set(BUILTIN_CFLAGS "")
+  add_security_warnings(BUILTIN_CFLAGS -1)
 
   if (COMPILER_RT_HAS_FCF_PROTECTION_FLAG)
     append_list_if(COMPILER_RT_ENABLE_CET -fcf-protection=full BUILTIN_CFLAGS)
diff --git a/compiler-rt/lib/builtins/eprintf.c b/compiler-rt/lib/builtins/eprintf.c
--- a/compiler-rt/lib/builtins/eprintf.c
+++ b/compiler-rt/lib/builtins/eprintf.c
@@ -15,6 +15,7 @@
 //
 // It should never be exported from a dylib, so it is marked
 // visibility hidden.
+#ifndef DONT_DEFINE_EPRINTF
 #ifndef _WIN32
 __attribute__((visibility("hidden")))
 #endif
@@ -25,3 +26,4 @@
   fflush(stderr);
   compilerrt_abort();
 }
+#endif
diff --git a/compiler-rt/lib/profile/InstrProfiling.c b/compiler-rt/lib/profile/InstrProfiling.c
--- a/compiler-rt/lib/profile/InstrProfiling.c
+++ b/compiler-rt/lib/profile/InstrProfiling.c
@@ -64,11 +64,11 @@
       CurrentVSiteCount += DI->NumValueSites[VKI];
 
     for (i = 0; i < CurrentVSiteCount; ++i) {
-      ValueProfNode *CurrentVNode = ValueCounters[i];
+      ValueProfNode *CurrVNode = ValueCounters[i];
 
-      while (CurrentVNode) {
-        CurrentVNode->Count = 0;
-        CurrentVNode = CurrentVNode->Next;
+      while (CurrVNode) {
+        CurrVNode->Count = 0;
+        CurrVNode = CurrVNode->Next;
       }
     }
   }
diff --git a/compiler-rt/lib/profile/InstrProfilingWriter.c b/compiler-rt/lib/profile/InstrProfilingWriter.c
--- a/compiler-rt/lib/profile/InstrProfilingWriter.c
+++ b/compiler-rt/lib/profile/InstrProfilingWriter.c
@@ -291,8 +291,8 @@
     // TODO: Unfortunately the header's fields are named DataSize and
     // CountersSize when they should be named NumData and NumCounters,
     // respectively.
-    const uint64_t CountersSize = NumCounters;
-    const uint64_t DataSize = NumData;
+    const uint64_t CountersSizeInitVal = NumCounters;
+    const uint64_t DataSizeInitVal = NumData;
 /* Initialize header structure.  */
 #define INSTR_PROF_RAW_HEADER(Type, Name, Init) Header.Name = Init;
 #include "profile/InstrProfData.inc"