diff --git a/compiler-rt/lib/asan/asan_rtl.cc b/compiler-rt/lib/asan/asan_rtl.cc
index 6f717081d2fd..b3a7b16f6591 100644
--- a/compiler-rt/lib/asan/asan_rtl.cc
+++ b/compiler-rt/lib/asan/asan_rtl.cc
@@ -48,7 +48,7 @@ void Die() {
 }
 
 void CheckFailed(const char *file, int line, const char *cond, u64 v1, u64 v2) {
-  AsanReport("AddressSanitizer CHECK failed: %s:%d \"%s\" (%zx, %zx)\n",
+  AsanReport("AddressSanitizer CHECK failed: %s:%d \"%s\" (0x%zx, 0x%zx)\n",
              file, line, cond, (uptr)v1, (uptr)v2);
   PRINT_CURRENT_STACK();
   ShowStatsAndAbort();
diff --git a/compiler-rt/lib/asan/asan_thread.cc b/compiler-rt/lib/asan/asan_thread.cc
index 2f2773212f73..a46ae2889785 100644
--- a/compiler-rt/lib/asan/asan_thread.cc
+++ b/compiler-rt/lib/asan/asan_thread.cc
@@ -26,6 +26,9 @@ AsanThread::AsanThread(LinkerInitialized x)
       malloc_storage_(x),
       stats_(x) { }
 
+static AsanLock mu_for_thread_summary(LINKER_INITIALIZED);
+static LowLevelAllocator allocator_for_thread_summary(LINKER_INITIALIZED);
+
 AsanThread *AsanThread::Create(u32 parent_tid, thread_callback_t start_routine,
                                void *arg, AsanStackTrace *stack) {
   uptr size = RoundUpTo(sizeof(AsanThread), kPageSize);
@@ -33,7 +36,15 @@ AsanThread *AsanThread::Create(u32 parent_tid, thread_callback_t start_routine,
   thread->start_routine_ = start_routine;
   thread->arg_ = arg;
 
-  AsanThreadSummary *summary = new AsanThreadSummary(parent_tid, stack);
+  const uptr kSummaryAllocSize = 1024;
+  CHECK_LE(sizeof(AsanThreadSummary), kSummaryAllocSize);
+  AsanThreadSummary *summary;
+  {
+    ScopedLock lock(&mu_for_thread_summary);
+    summary = (AsanThreadSummary*)
+        allocator_for_thread_summary.Allocate(kSummaryAllocSize);
+  }
+  summary->Init(parent_tid, stack);
   summary->set_thread(thread);
   thread->set_summary(summary);
 
diff --git a/compiler-rt/lib/asan/asan_thread.h b/compiler-rt/lib/asan/asan_thread.h
index 4d356cc742ae..9a032fe3e66c 100644
--- a/compiler-rt/lib/asan/asan_thread.h
+++ b/compiler-rt/lib/asan/asan_thread.h
@@ -18,6 +18,7 @@
 #include "asan_internal.h"
 #include "asan_stack.h"
 #include "asan_stats.h"
+#include "sanitizer_common/sanitizer_libc.h"
 
 namespace __asan {
 
@@ -30,12 +31,12 @@ class AsanThread;
 class AsanThreadSummary {
  public:
   explicit AsanThreadSummary(LinkerInitialized) { }  // for T0.
-  AsanThreadSummary(u32 parent_tid, AsanStackTrace *stack)
-      : parent_tid_(parent_tid),
-        announced_(false) {
+  void Init(u32 parent_tid, AsanStackTrace *stack) {
+    parent_tid_ = parent_tid;
+    announced_ = false;
     tid_ = kInvalidTid;
     if (stack) {
-      stack_ = *stack;
+      internal_memcpy(&stack_, stack, sizeof(*stack));
     }
     thread_ = 0;
   }