Index: compiler-rt/trunk/lib/sanitizer_common/sanitizer_flags.inc
===================================================================
--- compiler-rt/trunk/lib/sanitizer_common/sanitizer_flags.inc
+++ compiler-rt/trunk/lib/sanitizer_common/sanitizer_flags.inc
@@ -93,6 +93,9 @@
 COMMON_FLAG(HandleSignalMode, handle_sigfpe, kHandleSignalYes,
             COMMON_FLAG_HANDLE_SIGNAL_HELP(SIGFPE))
 #undef COMMON_FLAG_HANDLE_SIGNAL_HELP
+COMMON_FLAG(bool, allow_user_segv_handler, true,
+            "Deprecated. Thue has no effect, see handle_sigbus. If false, "
+            "handle_*=1 will be upgraded to handle_*=2.")
 COMMON_FLAG(bool, use_sigaltstack, true,
             "If set, uses alternate stack for signal handling.")
 COMMON_FLAG(bool, detect_deadlocks, false,
Index: compiler-rt/trunk/lib/sanitizer_common/sanitizer_linux.cc
===================================================================
--- compiler-rt/trunk/lib/sanitizer_common/sanitizer_linux.cc
+++ compiler-rt/trunk/lib/sanitizer_common/sanitizer_linux.cc
@@ -1396,7 +1396,7 @@
 
 #endif
 
-HandleSignalMode GetHandleSignalMode(int signum) {
+static HandleSignalMode GetHandleSignalModeImpl(int signum) {
   switch (signum) {
     case SIGABRT:
       return common_flags()->handle_abort;
@@ -1412,6 +1412,13 @@
   return kHandleSignalNo;
 }
 
+HandleSignalMode GetHandleSignalMode(int signum) {
+  HandleSignalMode result = GetHandleSignalModeImpl(signum);
+  if (result == kHandleSignalYes && !common_flags()->allow_user_segv_handler)
+    return kHandleSignalExclusive;
+  return result;
+}
+
 #if !SANITIZER_GO
 void *internal_start_thread(void(*func)(void *arg), void *arg) {
   // Start the thread with signals blocked, otherwise it can steal user signals.
Index: compiler-rt/trunk/lib/sanitizer_common/sanitizer_mac.cc
===================================================================
--- compiler-rt/trunk/lib/sanitizer_common/sanitizer_mac.cc
+++ compiler-rt/trunk/lib/sanitizer_common/sanitizer_mac.cc
@@ -414,10 +414,7 @@
   memory_mapping.DumpListOfModules(&modules_);
 }
 
-HandleSignalMode GetHandleSignalMode(int signum) {
-  // Handling fatal signals on watchOS and tvOS devices is disallowed.
-  if ((SANITIZER_WATCHOS || SANITIZER_TVOS) && !(SANITIZER_IOSSIM))
-    return kHandleSignalNo;
+static HandleSignalMode GetHandleSignalModeImpl(int signum) {
   switch (signum) {
     case SIGABRT:
       return common_flags()->handle_abort;
@@ -433,6 +430,16 @@
   return kHandleSignalNo;
 }
 
+HandleSignalMode GetHandleSignalMode(int signum) {
+  // Handling fatal signals on watchOS and tvOS devices is disallowed.
+  if ((SANITIZER_WATCHOS || SANITIZER_TVOS) && !(SANITIZER_IOSSIM))
+    return kHandleSignalNo;
+  HandleSignalMode result = GetHandleSignalModeImpl(signum);
+  if (result == kHandleSignalYes && !common_flags()->allow_user_segv_handler)
+    return kHandleSignalExclusive;
+  return result;
+}
+
 MacosVersion cached_macos_version = MACOS_VERSION_UNINITIALIZED;
 
 MacosVersion GetMacosVersionInternal() {
Index: compiler-rt/trunk/test/asan/TestCases/Posix/allow_user_segv.cc
===================================================================
--- compiler-rt/trunk/test/asan/TestCases/Posix/allow_user_segv.cc
+++ compiler-rt/trunk/test/asan/TestCases/Posix/allow_user_segv.cc
@@ -10,6 +10,14 @@
 // RUN: %clangxx_asan -O0 %s -o %t && %env_asan_opts=handle_segv=2 not %run %t 2>&1 | FileCheck %s --check-prefix=CHECK2
 // RUN: %clangxx_asan -O2 %s -o %t && %env_asan_opts=handle_segv=2 not %run %t 2>&1 | FileCheck %s --check-prefix=CHECK2
 
+// RUN: %clangxx_asan -O0 %s -o %t && %env_asan_opts=handle_segv=0:allow_user_segv_handler=0 not %run %t 2>&1 | FileCheck %s --check-prefix=CHECK0
+// RUN: %clangxx_asan -O0 %s -o %t && %env_asan_opts=handle_segv=1:allow_user_segv_handler=0 not %run %t 2>&1 | FileCheck %s --check-prefix=CHECK2
+// RUN: %clangxx_asan -O0 %s -o %t && %env_asan_opts=handle_segv=2:allow_user_segv_handler=0 not %run %t 2>&1 | FileCheck %s --check-prefix=CHECK2
+
+// RUN: %clangxx_asan -O0 %s -o %t && %env_asan_opts=handle_segv=0:allow_user_segv_handler=1 not %run %t 2>&1 | FileCheck %s --check-prefix=CHECK0
+// RUN: %clangxx_asan -O0 %s -o %t && %env_asan_opts=handle_segv=1:allow_user_segv_handler=1 not %run %t 2>&1 | FileCheck %s --check-prefix=CHECK1
+// RUN: %clangxx_asan -O0 %s -o %t && %env_asan_opts=handle_segv=2:allow_user_segv_handler=1 not %run %t 2>&1 | FileCheck %s --check-prefix=CHECK2
+
 #include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>