Index: lib/ubsan/CMakeLists.txt
===================================================================
--- lib/ubsan/CMakeLists.txt
+++ lib/ubsan/CMakeLists.txt
@@ -11,6 +11,7 @@
 set(UBSAN_STANDALONE_SOURCES
   ubsan_diag_standalone.cc
   ubsan_init_standalone.cc
+  ubsan_preinit.cc
   ubsan_signals_standalone.cc
   )
 
Index: lib/ubsan/ubsan_init.h
===================================================================
--- lib/ubsan/ubsan_init.h
+++ lib/ubsan/ubsan_init.h
@@ -13,6 +13,8 @@
 #ifndef UBSAN_INIT_H
 #define UBSAN_INIT_H
 
+#include "sanitizer_common/sanitizer_flags.h"
+
 namespace __ubsan {
 
 // Get the full tool name for UBSan.
@@ -29,6 +31,8 @@
 // from "parent tool" (e.g. ASan) initialization.
 void InitAsPlugin();
 
+extern "C" SANITIZER_INTERFACE_ATTRIBUTE void __ubsan_init();
+
 }  // namespace __ubsan
 
 #endif  // UBSAN_INIT_H
Index: lib/ubsan/ubsan_init_standalone.cc
===================================================================
--- lib/ubsan/ubsan_init_standalone.cc
+++ lib/ubsan/ubsan_init_standalone.cc
@@ -20,15 +20,20 @@
 #include "ubsan_init.h"
 #include "ubsan_signals_standalone.h"
 
+using namespace __ubsan;
+
+extern "C" void __ubsan_init() {
+  InitAsStandalone();
+  InitializeDeadlySignals();
+}
+
 namespace __ubsan {
 
 class UbsanStandaloneInitializer {
  public:
   UbsanStandaloneInitializer() {
-    InitAsStandalone();
-    InitializeDeadlySignals();
+    __ubsan_init();
   }
 };
 static UbsanStandaloneInitializer ubsan_standalone_initializer;
-
 } // namespace __ubsan
Index: lib/ubsan/ubsan_preinit.cc
===================================================================
--- /dev/null
+++ lib/ubsan/ubsan_preinit.cc
@@ -0,0 +1,22 @@
+//===-- ubsan_preinit.cc --------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Call __ubsan_init at the very early stage of process startup.
+//
+//===----------------------------------------------------------------------===//
+#include "ubsan_init.h"
+
+using namespace __ubsan;
+
+#if SANITIZER_CAN_USE_PREINIT_ARRAY
+  // The symbol is called __local_ubsan_preinit, because it's not intended to be
+  // exported.
+  __attribute__((section(".preinit_array"), used))
+  void (*__local_ubsan_preinit)(void) = __ubsan_init;
+#endif