Index: compiler-rt/trunk/CMakeLists.txt
===================================================================
--- compiler-rt/trunk/CMakeLists.txt
+++ compiler-rt/trunk/CMakeLists.txt
@@ -94,14 +94,17 @@
 if(APPLE AND SANITIZER_MIN_OSX_VERSION AND SANITIZER_MIN_OSX_VERSION VERSION_LESS "10.9")
   # Mac OS X prior to 10.9 had problems with exporting symbols from
   # libc++/libc++abi.
-  set(use_cxxabi_default OFF)
-elseif(MSVC)
-  set(use_cxxabi_default OFF)
+  set(cxxabi_supported OFF)
 else()
-  set(use_cxxabi_default ON)
+  set(cxxabi_supported ON)
 endif()
 
-option(SANITIZER_CAN_USE_CXXABI "Sanitizers can use cxxabi" ${use_cxxabi_default})
+option(SANITIZER_ALLOW_CXXABI "Allow use of C++ ABI details in ubsan" ON)
+
+set(SANITIZE_CAN_USE_CXXABI OFF)
+if (cxxabi_supported AND SANITIZER_ALLOW_CXXABI)
+  set(SANITIZER_CAN_USE_CXXABI ON)
+endif()
 pythonize_bool(SANITIZER_CAN_USE_CXXABI)
 
 set(SANITIZER_CXX_ABI "default" CACHE STRING
Index: compiler-rt/trunk/lib/ubsan/ubsan_handlers.h
===================================================================
--- compiler-rt/trunk/lib/ubsan/ubsan_handlers.h
+++ compiler-rt/trunk/lib/ubsan/ubsan_handlers.h
@@ -192,6 +192,13 @@
 /// \brief Handle control flow integrity failures.
 RECOVERABLE(cfi_check_fail, CFICheckFailData *Data, ValueHandle Function,
             uptr VtableIsValid)
+
+struct ReportOptions;
+
+extern "C" SANITIZER_INTERFACE_ATTRIBUTE void __ubsan_handle_cfi_bad_type(
+    CFICheckFailData *Data, ValueHandle Vtable, bool ValidVtable,
+    ReportOptions Opts);
+
 }
 
 #endif // UBSAN_HANDLERS_H
Index: compiler-rt/trunk/lib/ubsan/ubsan_handlers.cc
===================================================================
--- compiler-rt/trunk/lib/ubsan/ubsan_handlers.cc
+++ compiler-rt/trunk/lib/ubsan/ubsan_handlers.cc
@@ -652,16 +652,33 @@
 }
 
 namespace __ubsan {
+
 #ifdef UBSAN_CAN_USE_CXXABI
+
+#ifdef _WIN32
+
+extern "C" void __ubsan_handle_cfi_bad_type_default(CFICheckFailData *Data,
+                                                    ValueHandle Vtable,
+                                                    bool ValidVtable,
+                                                    ReportOptions Opts) {
+  Die();
+}
+
+WIN_WEAK_ALIAS(__ubsan_handle_cfi_bad_type, __ubsan_handle_cfi_bad_type_default)
+#else
 SANITIZER_WEAK_ATTRIBUTE
-void HandleCFIBadType(CFICheckFailData *Data, ValueHandle Vtable,
-                      bool ValidVtable, ReportOptions Opts);
+#endif
+void __ubsan_handle_cfi_bad_type(CFICheckFailData *Data, ValueHandle Vtable,
+                                 bool ValidVtable, ReportOptions Opts);
+
 #else
-static void HandleCFIBadType(CFICheckFailData *Data, ValueHandle Vtable,
-                             bool ValidVtable, ReportOptions Opts) {
+static void __ubsan_handle_cfi_bad_type(CFICheckFailData *Data,
+                                        ValueHandle Vtable,
+                                        bool ValidVtable, ReportOptions Opts) {
   Die();
 }
 #endif
+
 }  // namespace __ubsan
 
 void __ubsan::__ubsan_handle_cfi_check_fail(CFICheckFailData *Data,
@@ -671,7 +688,7 @@
   if (Data->CheckKind == CFITCK_ICall)
     handleCFIBadIcall(Data, Value, Opts);
   else
-    HandleCFIBadType(Data, Value, ValidVtable, Opts);
+    __ubsan_handle_cfi_bad_type(Data, Value, ValidVtable, Opts);
 }
 
 void __ubsan::__ubsan_handle_cfi_check_fail_abort(CFICheckFailData *Data,
@@ -681,7 +698,7 @@
   if (Data->CheckKind == CFITCK_ICall)
     handleCFIBadIcall(Data, Value, Opts);
   else
-    HandleCFIBadType(Data, Value, ValidVtable, Opts);
+    __ubsan_handle_cfi_bad_type(Data, Value, ValidVtable, Opts);
   Die();
 }
 
Index: compiler-rt/trunk/lib/ubsan/ubsan_handlers_cxx.cc
===================================================================
--- compiler-rt/trunk/lib/ubsan/ubsan_handlers_cxx.cc
+++ compiler-rt/trunk/lib/ubsan/ubsan_handlers_cxx.cc
@@ -95,8 +95,8 @@
 }
 
 namespace __ubsan {
-void HandleCFIBadType(CFICheckFailData *Data, ValueHandle Vtable,
-                      bool ValidVtable, ReportOptions Opts) {
+void __ubsan_handle_cfi_bad_type(CFICheckFailData *Data, ValueHandle Vtable,
+                                 bool ValidVtable, ReportOptions Opts) {
   SourceLocation Loc = Data->Loc.acquire();
   ErrorType ET = ErrorType::CFIBadType;
 
Index: compiler-rt/trunk/test/cfi/target_uninstrumented.cpp
===================================================================
--- compiler-rt/trunk/test/cfi/target_uninstrumented.cpp
+++ compiler-rt/trunk/test/cfi/target_uninstrumented.cpp
@@ -3,6 +3,7 @@
 // RUN: %t 2>&1 | FileCheck %s
 
 // REQUIRES: cxxabi
+// UNSUPPORTED: win32
 
 #include <stdio.h>
 #include <string.h>
Index: compiler-rt/trunk/test/ubsan/TestCases/TypeCheck/PR33221.cpp
===================================================================
--- compiler-rt/trunk/test/ubsan/TestCases/TypeCheck/PR33221.cpp
+++ compiler-rt/trunk/test/ubsan/TestCases/TypeCheck/PR33221.cpp
@@ -2,6 +2,7 @@
 // RUN: %run %t 2>&1 | FileCheck %s
 
 // REQUIRES: cxxabi
+// UNSUPPORTED: win32
 
 #include <string.h>
 
Index: compiler-rt/trunk/test/ubsan/TestCases/TypeCheck/vptr-non-unique-typeinfo.cpp
===================================================================
--- compiler-rt/trunk/test/ubsan/TestCases/TypeCheck/vptr-non-unique-typeinfo.cpp
+++ compiler-rt/trunk/test/ubsan/TestCases/TypeCheck/vptr-non-unique-typeinfo.cpp
@@ -3,6 +3,7 @@
 // RUN: %run %t
 //
 // REQUIRES: cxxabi
+// UNSUPPORTED: win32
 
 struct X {
   virtual ~X() {}
Index: compiler-rt/trunk/test/ubsan/TestCases/TypeCheck/vptr-virtual-base-construction.cpp
===================================================================
--- compiler-rt/trunk/test/ubsan/TestCases/TypeCheck/vptr-virtual-base-construction.cpp
+++ compiler-rt/trunk/test/ubsan/TestCases/TypeCheck/vptr-virtual-base-construction.cpp
@@ -2,6 +2,7 @@
 // RUN: %run %t
 
 // REQUIRES: cxxabi
+// UNSUPPORTED: win32
 
 int volatile n;
 
Index: compiler-rt/trunk/test/ubsan/TestCases/TypeCheck/vptr-virtual-base.cpp
===================================================================
--- compiler-rt/trunk/test/ubsan/TestCases/TypeCheck/vptr-virtual-base.cpp
+++ compiler-rt/trunk/test/ubsan/TestCases/TypeCheck/vptr-virtual-base.cpp
@@ -2,6 +2,7 @@
 // RUN: not %run %t 2>&1 | FileCheck %s
 
 // REQUIRES: cxxabi
+// UNSUPPORTED: win32
 
 struct S { virtual int f() { return 0; } };
 struct T : virtual S {};
Index: compiler-rt/trunk/test/ubsan/TestCases/TypeCheck/vptr.cpp
===================================================================
--- compiler-rt/trunk/test/ubsan/TestCases/TypeCheck/vptr.cpp
+++ compiler-rt/trunk/test/ubsan/TestCases/TypeCheck/vptr.cpp
@@ -26,6 +26,7 @@
 // RUN: %env_ubsan_opts=suppressions='"%t.loc-supp"' not %run %t x- 2>&1 | FileCheck %s --check-prefix=CHECK-LOC-SUPPRESS
 
 // REQUIRES: stable-runtime, cxxabi
+// UNSUPPORTED: win32
 #include <new>
 #include <assert.h>
 #include <stdio.h>