diff --git a/lib/Support/PrettyStackTrace.cpp b/lib/Support/PrettyStackTrace.cpp
index c111c5e..14290a1 100644
--- a/lib/Support/PrettyStackTrace.cpp
+++ b/lib/Support/PrettyStackTrace.cpp
@@ -15,11 +15,12 @@
 #include "llvm/Support/PrettyStackTrace.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/System/Signals.h"
+#include "llvm/System/ThreadLocal.h"
 #include "llvm/ADT/SmallString.h"
 using namespace llvm;
 
 // FIXME: This should be thread local when llvm supports threads.
-static const PrettyStackTraceEntry *PrettyStackTraceHead = 0;
+static sys::ThreadLocal<const PrettyStackTraceEntry> PrettyStackTraceHead;
 
 static unsigned PrintStack(const PrettyStackTraceEntry *Entry, raw_ostream &OS){
   unsigned NextID = 0;
@@ -34,12 +35,12 @@
 /// PrintCurStackTrace - Print the current stack trace to the specified stream.
 static void PrintCurStackTrace(raw_ostream &OS) {
   // Don't print an empty trace.
-  if (PrettyStackTraceHead == 0) return;
+  if (PrettyStackTraceHead.get() == 0) return;
   
   // If there are pretty stack frames registered, walk and emit them.
   OS << "Stack dump:\n";
   
-  PrintStack(PrettyStackTraceHead, OS);
+  PrintStack(PrettyStackTraceHead.get(), OS);
   OS.flush();
 }
 
@@ -84,14 +85,14 @@
   HandlerRegistered = HandlerRegistered;
     
   // Link ourselves.
-  NextEntry = PrettyStackTraceHead;
-  PrettyStackTraceHead = this;
+  NextEntry = PrettyStackTraceHead.get();
+  PrettyStackTraceHead.set(this);
 }
 
 PrettyStackTraceEntry::~PrettyStackTraceEntry() {
-  assert(PrettyStackTraceHead == this &&
+  assert(PrettyStackTraceHead.get() == this &&
          "Pretty stack trace entry destruction is out of order");
-  PrettyStackTraceHead = getNextEntry();
+  PrettyStackTraceHead.set(getNextEntry());
 }
 
 void PrettyStackTraceString::print(raw_ostream &OS) const {