Index: compiler-rt/trunk/lib/hwasan/hwasan.h
===================================================================
--- compiler-rt/trunk/lib/hwasan/hwasan.h
+++ compiler-rt/trunk/lib/hwasan/hwasan.h
@@ -152,6 +152,8 @@
 
 void UpdateMemoryUsage();
 
+void AppendToErrorMessageBuffer(const char *buffer);
+
 }  // namespace __hwasan
 
 #define HWASAN_MALLOC_HOOK(ptr, size)       \
Index: compiler-rt/trunk/lib/hwasan/hwasan.cc
===================================================================
--- compiler-rt/trunk/lib/hwasan/hwasan.cc
+++ compiler-rt/trunk/lib/hwasan/hwasan.cc
@@ -292,6 +292,7 @@
 
   MadviseShadow();
 
+  SetPrintfAndReportCallback(AppendToErrorMessageBuffer);
   // This may call libc -> needs initialized shadow.
   AndroidLogInit();
 
Index: compiler-rt/trunk/lib/hwasan/hwasan_linux.cc
===================================================================
--- compiler-rt/trunk/lib/hwasan/hwasan_linux.cc
+++ compiler-rt/trunk/lib/hwasan/hwasan_linux.cc
@@ -358,11 +358,10 @@
   GetStackTrace(stack, kStackTraceMax, StackTrace::GetNextInstructionPc(sig.pc),
                 sig.bp, uc, common_flags()->fast_unwind_on_fatal);
 
-  ReportTagMismatch(stack, ai.addr, ai.size, ai.is_store);
-
   ++hwasan_report_count;
-  if (flags()->halt_on_error || !ai.recover)
-    Die();
+
+  bool fatal = flags()->halt_on_error || !ai.recover;
+  ReportTagMismatch(stack, ai.addr, ai.size, ai.is_store, fatal);
 
 #if defined(__aarch64__)
   uc->uc_mcontext.pc += 4;
Index: compiler-rt/trunk/lib/hwasan/hwasan_report.h
===================================================================
--- compiler-rt/trunk/lib/hwasan/hwasan_report.h
+++ compiler-rt/trunk/lib/hwasan/hwasan_report.h
@@ -23,7 +23,7 @@
 
 void ReportStats();
 void ReportTagMismatch(StackTrace *stack, uptr addr, uptr access_size,
-                       bool is_store);
+                       bool is_store, bool fatal);
 void ReportInvalidFree(StackTrace *stack, uptr addr);
 
 void ReportAtExitStatistics();
Index: compiler-rt/trunk/lib/hwasan/hwasan_report.cc
===================================================================
--- compiler-rt/trunk/lib/hwasan/hwasan_report.cc
+++ compiler-rt/trunk/lib/hwasan/hwasan_report.cc
@@ -30,6 +30,49 @@
 
 namespace __hwasan {
 
+class ScopedReport {
+ public:
+  ScopedReport(bool fatal = false) : error_message_(1), fatal(fatal) {
+    BlockingMutexLock lock(&error_message_lock_);
+    error_message_ptr_ = fatal ? &error_message_ : nullptr;
+  }
+
+  ~ScopedReport() {
+    BlockingMutexLock lock(&error_message_lock_);
+    if (fatal) {
+      SetAbortMessage(error_message_.data());
+      Die();
+    }
+    error_message_ptr_ = nullptr;
+  }
+
+  static void MaybeAppendToErrorMessage(const char *msg) {
+    BlockingMutexLock lock(&error_message_lock_);
+    if (!error_message_ptr_)
+      return;
+    uptr len = internal_strlen(msg);
+    uptr old_size = error_message_ptr_->size();
+    error_message_ptr_->resize(old_size + len);
+    // overwrite old trailing '\0', keep new trailing '\0' untouched.
+    internal_memcpy(&(*error_message_ptr_)[old_size - 1], msg, len);
+  }
+ private:
+  ScopedErrorReportLock error_report_lock_;
+  InternalMmapVector<char> error_message_;
+  bool fatal;
+
+  static InternalMmapVector<char> *error_message_ptr_;
+  static BlockingMutex error_message_lock_;
+};
+
+InternalMmapVector<char> *ScopedReport::error_message_ptr_;
+BlockingMutex ScopedReport::error_message_lock_;
+
+// If there is an active ScopedReport, append to its error message.
+void AppendToErrorMessageBuffer(const char *buffer) {
+  ScopedReport::MaybeAppendToErrorMessage(buffer);
+}
+
 static StackTrace GetStackTraceFromId(u32 id) {
   CHECK(id);
   StackTrace res = StackDepotGet(id);
@@ -255,7 +298,8 @@
 }
 
 void ReportInvalidFree(StackTrace *stack, uptr tagged_addr) {
-  ScopedErrorReportLock l;
+  ScopedReport R(flags()->halt_on_error);
+
   uptr untagged_addr = UntagAddr(tagged_addr);
   tag_t ptr_tag = GetTagFromPointer(tagged_addr);
   tag_t *tag_ptr = reinterpret_cast<tag_t*>(MemToShadow(untagged_addr));
@@ -277,12 +321,11 @@
   PrintTagsAroundAddr(tag_ptr);
 
   ReportErrorSummary(bug_type, stack);
-  Die();
 }
 
 void ReportTagMismatch(StackTrace *stack, uptr tagged_addr, uptr access_size,
-                       bool is_store) {
-  ScopedErrorReportLock l;
+                       bool is_store, bool fatal) {
+  ScopedReport R(fatal);
   SavedStackAllocations current_stack_allocations(
       GetCurrentThread()->stack_allocations());
 
Index: compiler-rt/trunk/test/hwasan/TestCases/abort-message-android.cc
===================================================================
--- compiler-rt/trunk/test/hwasan/TestCases/abort-message-android.cc
+++ compiler-rt/trunk/test/hwasan/TestCases/abort-message-android.cc
@@ -0,0 +1,28 @@
+// RUN: %clangxx_hwasan -DERR=1 %s -o %t && not %run %t 2>&1 | FileCheck %s
+// RUN: %clangxx_hwasan -DERR=2 %s -o %t && not %run %t 2>&1 | FileCheck %s
+// REQUIRES: android
+
+#include <stdlib.h>
+#include <stdio.h>
+
+#include <sanitizer/hwasan_interface.h>
+
+__attribute__((no_sanitize("hwaddress")))
+extern "C" void android_set_abort_message(const char *msg) {
+  fprintf(stderr, "== abort message start\n%s\n== abort message end\n", msg);
+}
+
+int main() {
+  __hwasan_enable_allocator_tagging();
+  char *volatile p = (char *)malloc(16);
+  if (ERR==1) {
+    p[16] = 1;
+  } else {
+    free(p);
+    free(p);
+  }
+  // CHECK: ERROR: HWAddressSanitizer:
+  // CHECK: == abort message start
+  // CHECK: ERROR: HWAddressSanitizer:
+  // CHECK: == abort message end
+}