Index: llvm/include/llvm/ADT/BitVector.h
===================================================================
--- llvm/include/llvm/ADT/BitVector.h
+++ llvm/include/llvm/ADT/BitVector.h
@@ -759,7 +759,9 @@
   }
   bool isInvalid() const { return Size == (unsigned)-1; }
 
-  ArrayRef<BitWord> getData() const { return Bits; }
+  ArrayRef<BitWord> getData() const {
+    return Bits.take_front(NumBitWords(size()));
+  }
 
   //===--------------------------------------------------------------------===//
   // Portable bit mask operations.
Index: llvm/include/llvm/ADT/SmallBitVector.h
===================================================================
--- llvm/include/llvm/ADT/SmallBitVector.h
+++ llvm/include/llvm/ADT/SmallBitVector.h
@@ -668,8 +668,18 @@
   }
   bool isInvalid() const { return X == (uintptr_t)-1; }
 
-  ArrayRef<uintptr_t> getData() const {
-    return isSmall() ? makeArrayRef(X) : getPointer()->getData();
+  unsigned getDenseMapHashValue() const {
+    using HashType = std::pair<size_type, ArrayRef<uintptr_t>>;
+    HashType H;
+    H.first = size();
+    uintptr_t Word;
+    if (isSmall()) {
+      Word = getSmallBits();
+      H.second = ArrayRef<uintptr_t>(Word);
+    } else {
+      H.second = getPointer()->getData();
+    }
+    return DenseMapInfo<HashType>::getHashValue(H);
   }
 
 private:
@@ -717,8 +727,7 @@
     return V;
   }
   static unsigned getHashValue(const SmallBitVector &V) {
-    return DenseMapInfo<std::pair<unsigned, ArrayRef<uintptr_t>>>::getHashValue(
-        std::make_pair(V.size(), V.getData()));
+    return V.getDenseMapHashValue();
   }
   static bool isEqual(const SmallBitVector &LHS, const SmallBitVector &RHS) {
     if (LHS.isInvalid() || RHS.isInvalid())
Index: llvm/unittests/ADT/BitVectorTest.cpp
===================================================================
--- llvm/unittests/ADT/BitVectorTest.cpp
+++ llvm/unittests/ADT/BitVectorTest.cpp
@@ -1229,4 +1229,34 @@
   EXPECT_EQ(true, Set.erase(A));
   EXPECT_EQ(0U, Set.size());
 }
+
+/// Test that capacity doesn't affect hashing.
+TYPED_TEST(BitVectorTest, DenseMapHashing) {
+  using DMI = DenseMapInfo<TypeParam>;
+  {
+    TypeParam A;
+    A.resize(200);
+    A.set(100);
+
+    TypeParam B;
+    B.resize(200);
+    B.set(100);
+    B.reserve(1000);
+
+    EXPECT_EQ(DMI::getHashValue(A), DMI::getHashValue(B));
+  }
+  {
+    TypeParam A;
+    A.resize(20);
+    A.set(10);
+
+    TypeParam B;
+    B.resize(20);
+    B.set(10);
+    B.reserve(1000);
+
+    EXPECT_EQ(DMI::getHashValue(A), DMI::getHashValue(B));
+  }
+}
+
 } // namespace