Index: lib/ubsan/CMakeLists.txt
===================================================================
--- lib/ubsan/CMakeLists.txt
+++ lib/ubsan/CMakeLists.txt
@@ -9,6 +9,7 @@
   )
 
 set(UBSAN_STANDALONE_SOURCES
+  ubsan_diag_standalone.cc
   ubsan_init_standalone.cc
   )
 
Index: lib/ubsan/ubsan_diag_standalone.cc
===================================================================
--- /dev/null
+++ lib/ubsan/ubsan_diag_standalone.cc
@@ -0,0 +1,33 @@
+//===-- ubsan_diag_standalone.cc ------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Diagnostic reporting for the standalone UBSan runtime.
+//
+//===----------------------------------------------------------------------===//
+
+#include "ubsan_platform.h"
+#if CAN_SANITIZE_UB
+#include "ubsan_diag.h"
+
+using namespace __ubsan;
+
+extern "C" {
+SANITIZER_INTERFACE_ATTRIBUTE
+void __sanitizer_print_stack_trace() {
+  if (StackTrace::WillUseFastUnwind(false))
+    return;
+
+  GET_REPORT_OPTIONS(false);
+  BufferedStackTrace stack;
+  stack.Unwind(kStackTraceMax, Opts.pc, Opts.bp, 0, 0, 0, false);
+  stack.Print();
+}
+} // extern "C"
+
+#endif  // CAN_SANITIZE_UB