Index: include/llvm/Support/Timer.h
===================================================================
--- include/llvm/Support/Timer.h
+++ include/llvm/Support/Timer.h
@@ -98,7 +98,7 @@
     assert(!TG && !T.TG && "Can only assign uninit timers");
     return *this;
   }
-  ~Timer();
+  virtual ~Timer();
 
   /// Create an uninitialized timer, client must use 'init'.
   explicit Timer() {}
@@ -118,10 +118,10 @@
   /// Start the timer running.  Time between calls to startTimer/stopTimer is
   /// counted by the Timer class.  Note that these calls must be correctly
   /// paired.
-  void startTimer();
+  virtual void startTimer();
 
   /// Stop the timer.
-  void stopTimer();
+  virtual void stopTimer();
 
   /// Clear the timer state.
   void clear();
@@ -133,6 +133,26 @@
   friend class TimerGroup;
 };
 
+/// Whereas the Timer class enforces that calls to startTimer must be followed
+/// by a call to stopTimer, this "reference-counted" RefCntTimer allows
+/// multiple calls to startTimer, as long as they are paired with the same
+/// number of calls to stopTimer.  This is useful when, for example, timing a
+/// function that calls itself recursively.
+class RefCntTimer : public Timer {
+  unsigned RefCount = 0;
+public:
+  using Timer::Timer;
+
+  /// Start the timer running.  Time between calls to startTimer/stopTimer is
+  /// counted by the RefCntTimer class.  You may call startTimer multiple times
+  /// in succession, but stopTimer must also eventually be called the same
+  /// number of times.
+  void startTimer();
+
+  /// Stop the timer.
+  void stopTimer();
+};
+
 /// The TimeRegion class is used as a helper class to call the startTimer() and
 /// stopTimer() methods of the Timer class.  When the object is constructed, it
 /// starts the timer specified as its argument.  When it is destroyed, it stops
Index: lib/Support/Timer.cpp
===================================================================
--- lib/Support/Timer.cpp
+++ lib/Support/Timer.cpp
@@ -142,6 +142,17 @@
   Time -= StartTime;
 }
 
+void RefCntTimer::startTimer() {
+  if (RefCount == 0) Timer::startTimer();
+  RefCount += 1;
+}
+
+void RefCntTimer::stopTimer() {
+  assert(RefCount != 0 && "Cannot stop a reference counted timer more times than it has been started");
+  RefCount -= 1;
+  if (RefCount == 0) Timer::stopTimer();
+}
+
 void Timer::clear() {
   Running = Triggered = false;
   Time = StartTime = TimeRecord();
Index: unittests/Support/TimerTest.cpp
===================================================================
--- unittests/Support/TimerTest.cpp
+++ unittests/Support/TimerTest.cpp
@@ -62,4 +62,26 @@
   EXPECT_FALSE(T1.hasTriggered());
 }
 
+class Recurser {
+public:
+  RefCntTimer T;
+  Recurser() : T("RCT1", "RCT1") {}
+  void Recurse(unsigned Depth) {
+    T.startTimer();
+    if (Depth < 1)
+      Recurse(Depth + 1);
+    T.stopTimer();
+  }
+};
+
+TEST(RefCntTimer, Recurse) {
+  Recurser R;
+  ASSERT_FALSE(R.T.hasTriggered());
+  ASSERT_FALSE(R.T.isRunning());
+
+  R.Recurse(0);
+  ASSERT_TRUE(R.T.hasTriggered());
+  ASSERT_FALSE(R.T.isRunning());
+}
+
 } // end anon namespace