diff --git a/include/llvm/ADT/DenseMap.h b/include/llvm/ADT/DenseMap.h
index 78caba52a51..8b25a82e6ac 100644
--- a/include/llvm/ADT/DenseMap.h
+++ b/include/llvm/ADT/DenseMap.h
@@ -91,6 +91,8 @@ public:
   unsigned size() const { return NumEntries; }
   
   void clear() {
+    // If the capacity of the array is huge, and the # elements used is small,
+    // shrink the array.
     if (NumEntries * 4 < NumBuckets && NumBuckets > 64) {
       shrink_and_clear();
       return;
diff --git a/include/llvm/ADT/SmallPtrSet.h b/include/llvm/ADT/SmallPtrSet.h
index e39a4fe7064..2ff7de448fd 100644
--- a/include/llvm/ADT/SmallPtrSet.h
+++ b/include/llvm/ADT/SmallPtrSet.h
@@ -80,6 +80,11 @@ public:
   }
   
   void clear() {
+    // If the capacity of the array is huge, and the # elements used is small,
+    // shrink the array.
+    if (!isSmall() && NumElements*4 < CurArraySize && CurArraySize > 32)
+      return shrink_and_clear();
+    
     // Fill the array with empty markers.
     memset(CurArray, -1, CurArraySize*sizeof(void*));
     NumElements = 0;
@@ -103,8 +108,8 @@ public:
   bool count(void * const Ptr) const {
     if (isSmall()) {
       // Linear search for the item.
-      for (const void *const *APtr = SmallArray, *const *E = SmallArray+NumElements;
-           APtr != E; ++APtr)
+      for (const void *const *APtr = SmallArray,
+                      *const *E = SmallArray+NumElements; APtr != E; ++APtr)
         if (*APtr == Ptr)
           return true;
       return false;
@@ -121,6 +126,7 @@ private:
     return ((uintptr_t)Ptr >> 4) & (CurArraySize-1);
   }
   const void * const *FindBucketFor(const void *Ptr) const;
+  void shrink_and_clear();
   
   /// Grow - Allocate a larger backing store for the buckets and move it over.
   void Grow();
diff --git a/lib/Support/SmallPtrSet.cpp b/lib/Support/SmallPtrSet.cpp
index 1507059f386..ba00d903658 100644
--- a/lib/Support/SmallPtrSet.cpp
+++ b/lib/Support/SmallPtrSet.cpp
@@ -18,6 +18,24 @@
 
 using namespace llvm;
 
+void SmallPtrSetImpl::shrink_and_clear() {
+  assert(!isSmall() && "Can't shrink a small set!");
+  free(CurArray);
+
+  // Reduce the number of buckets.
+  CurArraySize = NumElements > 16 ? 1 << (Log2_32_Ceil(NumElements) + 1) : 32;
+  NumElements = NumTombstones = 0;
+
+  // Install the new array.  Clear all the buckets to empty.
+  CurArray = (const void**)malloc(sizeof(void*) * (CurArraySize+1));
+  assert(CurArray && "Failed to allocate memory?");
+  memset(CurArray, -1, CurArraySize*sizeof(void*));
+  
+  // The end pointer, always valid, is set to a valid element to help the
+  // iterator.
+  CurArray[CurArraySize] = 0;
+}
+
 bool SmallPtrSetImpl::insert(const void * Ptr) {
   if (isSmall()) {
     // Check to see if it is already in the set.