diff --git a/llvm/include/llvm/ADT/BitVector.h b/llvm/include/llvm/ADT/BitVector.h
--- a/llvm/include/llvm/ADT/BitVector.h
+++ b/llvm/include/llvm/ADT/BitVector.h
@@ -452,6 +452,9 @@
     return (Bits[Idx / BITWORD_SIZE] & Mask) != 0;
   }
 
+  /// Return the last element in the vector.
+  bool back() const { return (*this)[size() - 1]; }
+
   bool test(unsigned Idx) const {
     return (*this)[Idx];
   }
@@ -473,6 +476,9 @@
       set(OldSize);
   }
 
+  /// Pop one bit from the end of the vector.
+  void pop_back() { resize(size() - 1); }
+
   /// Test if any common bits are set.
   bool anyCommon(const BitVector &RHS) const {
     unsigned ThisWords = Bits.size();
diff --git a/llvm/include/llvm/ADT/SmallBitVector.h b/llvm/include/llvm/ADT/SmallBitVector.h
--- a/llvm/include/llvm/ADT/SmallBitVector.h
+++ b/llvm/include/llvm/ADT/SmallBitVector.h
@@ -471,6 +471,9 @@
     return getPointer()->operator[](Idx);
   }
 
+  /// Return the last element in the vector.
+  bool back() const { return (*this)[size() - 1]; }
+
   bool test(unsigned Idx) const {
     return (*this)[Idx];
   }
@@ -480,6 +483,9 @@
     resize(size() + 1, Val);
   }
 
+  /// Pop one bit from the end of the vector.
+  void pop_back() { resize(size() - 1); }
+
   /// Test if any common bits are set.
   bool anyCommon(const SmallBitVector &RHS) const {
     if (isSmall() && RHS.isSmall())
diff --git a/llvm/unittests/ADT/BitVectorTest.cpp b/llvm/unittests/ADT/BitVectorTest.cpp
--- a/llvm/unittests/ADT/BitVectorTest.cpp
+++ b/llvm/unittests/ADT/BitVectorTest.cpp
@@ -1180,21 +1180,25 @@
   EXPECT_EQ(-1, Vec.find_first());
   EXPECT_EQ(10U, Vec.size());
   EXPECT_EQ(0U, Vec.count());
+  EXPECT_EQ(false, Vec.back());
 
   Vec.push_back(true);
   EXPECT_EQ(10, Vec.find_first());
   EXPECT_EQ(11U, Vec.size());
   EXPECT_EQ(1U, Vec.count());
+  EXPECT_EQ(true, Vec.back());
 
   Vec.push_back(false);
   EXPECT_EQ(10, Vec.find_first());
   EXPECT_EQ(12U, Vec.size());
   EXPECT_EQ(1U, Vec.count());
+  EXPECT_EQ(false, Vec.back());
 
   Vec.push_back(true);
   EXPECT_EQ(10, Vec.find_first());
   EXPECT_EQ(13U, Vec.size());
   EXPECT_EQ(2U, Vec.count());
+  EXPECT_EQ(true, Vec.back());
 
   // Add a lot of values to cause reallocation.
   for (int i = 0; i != 100; ++i) {
@@ -1206,6 +1210,28 @@
   EXPECT_EQ(102U, Vec.count());
 }
 
+TYPED_TEST(BitVectorTest, PopBack) {
+  TypeParam Vec(10, true);
+  EXPECT_EQ(10U, Vec.size());
+  EXPECT_EQ(10U, Vec.count());
+  EXPECT_EQ(true, Vec.back());
+
+  Vec.pop_back();
+  EXPECT_EQ(9U, Vec.size());
+  EXPECT_EQ(9U, Vec.count());
+  EXPECT_EQ(true, Vec.back());
+
+  Vec.push_back(false);
+  EXPECT_EQ(10U, Vec.size());
+  EXPECT_EQ(9U, Vec.count());
+  EXPECT_EQ(false, Vec.back());
+
+  Vec.pop_back();
+  EXPECT_EQ(9U, Vec.size());
+  EXPECT_EQ(9U, Vec.count());
+  EXPECT_EQ(true, Vec.back());
+}
+
 TYPED_TEST(BitVectorTest, DenseSet) {
   DenseSet<TypeParam> Set;
   TypeParam A(10, true);