Index: lib/sanitizer_common/CMakeLists.txt
===================================================================
--- lib/sanitizer_common/CMakeLists.txt
+++ lib/sanitizer_common/CMakeLists.txt
@@ -58,6 +58,7 @@
 
 set(SANITIZER_LIBCDEP_SOURCES
   sanitizer_common_libcdep.cc
+  sanitizer_allocator_checks.cc
   sancov_flags.cc
   sanitizer_coverage_fuchsia.cc
   sanitizer_coverage_libcdep_new.cc
Index: lib/sanitizer_common/sanitizer_allocator_checks.h
===================================================================
--- lib/sanitizer_common/sanitizer_allocator_checks.h
+++ lib/sanitizer_common/sanitizer_allocator_checks.h
@@ -15,17 +15,22 @@
 #ifndef SANITIZER_ALLOCATOR_CHECKS_H
 #define SANITIZER_ALLOCATOR_CHECKS_H
 
-#include "sanitizer_errno.h"
 #include "sanitizer_internal_defs.h"
 #include "sanitizer_common.h"
 #include "sanitizer_platform.h"
 
 namespace __sanitizer {
 
+// The following is defined in a separate compilation unit to avoid pulling in
+// sanitizer_errno.h in this header, which leads to conflicts when other system
+// headers include errno.h. This is usually the result of an unlikely event,
+// and as such we do not care as much about having it inlined.
+void SetErrnoToENOMEM();
+
 // A common errno setting logic shared by almost all sanitizer allocator APIs.
 INLINE void *SetErrnoOnNull(void *ptr) {
   if (UNLIKELY(!ptr))
-    errno = errno_ENOMEM;
+    SetErrnoToENOMEM();
   return ptr;
 }
 
Index: lib/sanitizer_common/sanitizer_allocator_checks.cc
===================================================================
--- /dev/null
+++ lib/sanitizer_common/sanitizer_allocator_checks.cc
@@ -0,0 +1,23 @@
+//===-- sanitizer_allocator_checks.cc ---------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Various checks shared between ThreadSanitizer, MemorySanitizer, etc. memory
+// allocators.
+//
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_errno.h"
+
+namespace __sanitizer {
+
+void SetErrnoToENOMEM() {
+  errno = errno_ENOMEM;
+}
+
+} // namespace __sanitizer
Index: lib/tsan/rtl/tsan_mman.cc
===================================================================
--- lib/tsan/rtl/tsan_mman.cc
+++ lib/tsan/rtl/tsan_mman.cc
@@ -13,6 +13,7 @@
 #include "sanitizer_common/sanitizer_allocator_checks.h"
 #include "sanitizer_common/sanitizer_allocator_interface.h"
 #include "sanitizer_common/sanitizer_common.h"
+#include "sanitizer_common/sanitizer_errno.h"
 #include "sanitizer_common/sanitizer_placement_new.h"
 #include "tsan_mman.h"
 #include "tsan_rtl.h"