diff --git a/include/llvm/ADT/DenseMap.h b/include/llvm/ADT/DenseMap.h
index 28a7b68a219..85f37b9051b 100644
--- a/include/llvm/ADT/DenseMap.h
+++ b/include/llvm/ADT/DenseMap.h
@@ -43,7 +43,7 @@ protected:
   typedef std::pair<KeyT, ValueT> BucketT;
 
 public:
-  typedef size_t size_type;
+  typedef unsigned size_type;
   typedef KeyT key_type;
   typedef ValueT mapped_type;
   typedef BucketT value_type;
diff --git a/include/llvm/ADT/DenseSet.h b/include/llvm/ADT/DenseSet.h
index d74c6a89b21..37a81b0c7ee 100644
--- a/include/llvm/ADT/DenseSet.h
+++ b/include/llvm/ADT/DenseSet.h
@@ -29,7 +29,7 @@ class DenseSet {
 public:
   typedef ValueT key_type;
   typedef ValueT value_type;
-  typedef size_t size_type;
+  typedef unsigned size_type;
 
   explicit DenseSet(unsigned NumInitBuckets = 0) : TheMap(NumInitBuckets) {}
 
diff --git a/include/llvm/ADT/ScopedHashTable.h b/include/llvm/ADT/ScopedHashTable.h
index a9ff70e204a..02a6ea34583 100644
--- a/include/llvm/ADT/ScopedHashTable.h
+++ b/include/llvm/ADT/ScopedHashTable.h
@@ -148,7 +148,7 @@ public:
   /// ScopeTy - This is a helpful typedef that allows clients to get easy access
   /// to the name of the scope for this hash table.
   typedef ScopedHashTableScope<K, V, KInfo, AllocatorTy> ScopeTy;
-  typedef size_t size_type;
+  typedef unsigned size_type;
 private:
   typedef ScopedHashTableVal<K, V> ValTy;
   DenseMap<K, ValTy*, KInfo> TopLevelMap;
diff --git a/include/llvm/ADT/SmallBitVector.h b/include/llvm/ADT/SmallBitVector.h
index 18c68fdd4d2..1e49e27001c 100644
--- a/include/llvm/ADT/SmallBitVector.h
+++ b/include/llvm/ADT/SmallBitVector.h
@@ -54,7 +54,7 @@ class SmallBitVector {
   };
 
 public:
-  typedef size_t size_type;
+  typedef unsigned size_type;
   // Encapsulation of a single bit.
   class reference {
     SmallBitVector &TheVector;
diff --git a/include/llvm/ADT/SmallPtrSet.h b/include/llvm/ADT/SmallPtrSet.h
index 45b2256bdf7..74f3fd43cec 100644
--- a/include/llvm/ADT/SmallPtrSet.h
+++ b/include/llvm/ADT/SmallPtrSet.h
@@ -73,7 +73,7 @@ protected:
   ~SmallPtrSetImplBase();
 
 public:
-  typedef size_t size_type;
+  typedef unsigned size_type;
   bool LLVM_ATTRIBUTE_UNUSED_RESULT empty() const { return size() == 0; }
   size_type size() const { return NumElements; }
 
diff --git a/include/llvm/ADT/SparseBitVector.h b/include/llvm/ADT/SparseBitVector.h
index 16106a7d630..36754d68235 100644
--- a/include/llvm/ADT/SparseBitVector.h
+++ b/include/llvm/ADT/SparseBitVector.h
@@ -45,7 +45,7 @@ struct SparseBitVectorElement
   : public ilist_node<SparseBitVectorElement<ElementSize> > {
 public:
   typedef unsigned long BitWord;
-  typedef size_t size_type;
+  typedef unsigned size_type;
   enum {
     BITWORD_SIZE = sizeof(BitWord) * CHAR_BIT,
     BITWORDS_PER_ELEMENT = (ElementSize + BITWORD_SIZE - 1) / BITWORD_SIZE,
diff --git a/include/llvm/ADT/SparseMultiSet.h b/include/llvm/ADT/SparseMultiSet.h
index 92b9d835b70..dc1273eb7ff 100644
--- a/include/llvm/ADT/SparseMultiSet.h
+++ b/include/llvm/ADT/SparseMultiSet.h
@@ -185,7 +185,7 @@ public:
   typedef const ValueT &const_reference;
   typedef ValueT *pointer;
   typedef const ValueT *const_pointer;
-  typedef size_t size_type;
+  typedef unsigned size_type;
 
   SparseMultiSet()
     : Sparse(nullptr), Universe(0), FreelistIdx(SMSNode::INVALID), NumFree(0) {}
diff --git a/include/llvm/ADT/SparseSet.h b/include/llvm/ADT/SparseSet.h
index e347667b4dc..632d52ad9d8 100644
--- a/include/llvm/ADT/SparseSet.h
+++ b/include/llvm/ADT/SparseSet.h
@@ -124,7 +124,7 @@ class SparseSet {
 
   typedef typename KeyFunctorT::argument_type KeyT;
   typedef SmallVector<ValueT, 8> DenseT;
-  typedef size_t size_type;
+  typedef unsigned size_type;
   DenseT Dense;
   SparseT *Sparse;
   unsigned Universe;
diff --git a/include/llvm/IR/ValueMap.h b/include/llvm/IR/ValueMap.h
index e459e4904c6..3d575ac874d 100644
--- a/include/llvm/IR/ValueMap.h
+++ b/include/llvm/IR/ValueMap.h
@@ -87,7 +87,7 @@ public:
   typedef KeyT key_type;
   typedef ValueT mapped_type;
   typedef std::pair<KeyT, ValueT> value_type;
-  typedef size_t size_type;
+  typedef unsigned size_type;
 
   explicit ValueMap(unsigned NumInitBuckets = 64)
     : Map(NumInitBuckets), Data() {}