Index: include/llvm/ADT/STLExtras.h
===================================================================
--- include/llvm/ADT/STLExtras.h
+++ include/llvm/ADT/STLExtras.h
@@ -26,6 +26,7 @@
 #include <memory>
 #include <utility> // for std::pair
 
+#include "llvm/ADT/iterator.h"
 #include "llvm/ADT/iterator_range.h"
 #include "llvm/Support/Compiler.h"
 
@@ -235,6 +236,89 @@
                     llvm::make_reverse_iterator(std::begin(C)));
 }
 
+/// An iterator adaptor that filters the elements of given inner iterators.
+///
+/// The predicate parameter should be a callable object that accepts the wrapped
+/// iterator's reference type and returns a bool. When incrementing or
+/// decrementing the iterator, it will call the predicate on each element and
+/// skip any where it returns false.
+///
+/// \code
+///   int A[] = { 1, 2, 3, 4 };
+///   const auto R = make_filter_range(A, A + 4,
+///                                    [](int A) { return A % 2 == 1; });
+///   // R contains { 1, 3 }.
+/// \endcode
+template <typename WrappedIteratorT, typename Predicate>
+class filter_iterator
+    : public iterator_adaptor_base<
+          filter_iterator<WrappedIteratorT, Predicate>, WrappedIteratorT,
+          typename std::common_type<
+              std::bidirectional_iterator_tag,
+              typename std::iterator_traits<
+                  WrappedIteratorT>::iterator_category>::type,
+          typename std::iterator_traits<WrappedIteratorT>::value_type,
+          typename std::iterator_traits<WrappedIteratorT>::difference_type,
+          typename std::iterator_traits<WrappedIteratorT>::pointer,
+          typename std::iterator_traits<WrappedIteratorT>::reference> {
+  using IteratorCategoryT = typename std::common_type<
+      std::bidirectional_iterator_tag,
+      typename std::iterator_traits<WrappedIteratorT>::iterator_category>::type;
+  using BaseT = iterator_adaptor_base<
+      filter_iterator<WrappedIteratorT, Predicate>, WrappedIteratorT,
+      IteratorCategoryT,
+      typename std::iterator_traits<WrappedIteratorT>::value_type,
+      typename std::iterator_traits<WrappedIteratorT>::difference_type,
+      typename std::iterator_traits<WrappedIteratorT>::pointer,
+      typename std::iterator_traits<WrappedIteratorT>::reference>;
+
+  WrappedIteratorT End;
+  Predicate Pred;
+
+  void findNextValid() {
+    while (this->I != End && !Pred(*this->I))
+      BaseT::operator++();
+  }
+
+public:
+  filter_iterator(WrappedIteratorT Begin, WrappedIteratorT End, Predicate Pred)
+      : BaseT(Begin), End(End), Pred(Pred) {
+    findNextValid();
+  }
+
+  using BaseT::operator++;
+  using BaseT::operator--;
+
+  filter_iterator &operator++() {
+    BaseT::operator++();
+    findNextValid();
+    return *this;
+  }
+
+  filter_iterator &operator--() {
+    static_assert(
+        std::is_same<std::bidirectional_iterator_tag, IteratorCategoryT>::value,
+        "operator--() reuiqres the underlying type to be at least "
+        "bidirectional");
+    BaseT::operator--();
+    // Hopefully users don't call operator--() on Begin. They will be doomed.
+    while (!Pred(*this->I))
+      BaseT::operator--();
+    return *this;
+  }
+};
+
+/// \brief Convenience function that takes a range of elements and a predicate,
+/// and return a new filter_iterator range.
+template <typename WrappedIteratorT, typename Predicate>
+iterator_range<filter_iterator<WrappedIteratorT, Predicate>>
+make_filter_range(iterator_range<WrappedIteratorT> Range,
+                  const Predicate &Pred) {
+  using IterT = filter_iterator<WrappedIteratorT, Predicate>;
+  return make_range(IterT(Range.begin(), Range.end(), Pred),
+                    IterT(Range.end(), Range.end(), Pred));
+}
+
 //===----------------------------------------------------------------------===//
 //     Extra additions to <utility>
 //===----------------------------------------------------------------------===//
Index: include/llvm/ADT/iterator.h
===================================================================
--- include/llvm/ADT/iterator.h
+++ include/llvm/ADT/iterator.h
@@ -168,15 +168,7 @@
 
   iterator_adaptor_base() = default;
 
-  template <typename U>
-  explicit iterator_adaptor_base(
-      U &&u,
-      typename std::enable_if<
-          !std::is_base_of<typename std::remove_cv<
-                               typename std::remove_reference<U>::type>::type,
-                           DerivedT>::value,
-          int>::type = 0)
-      : I(std::forward<U &&>(u)) {}
+  explicit iterator_adaptor_base(WrappedIteratorT u) : I(std::move(u)) {}
 
   const WrappedIteratorT &wrapped() const { return I; }
 
Index: unittests/Support/IteratorTest.cpp
===================================================================
--- unittests/Support/IteratorTest.cpp
+++ unittests/Support/IteratorTest.cpp
@@ -12,6 +12,8 @@
 #include "llvm/ADT/SmallVector.h"
 #include "gtest/gtest.h"
 
+#include <functional>
+
 using namespace llvm;
 
 namespace {
@@ -98,4 +100,77 @@
   EXPECT_EQ(End, I);
 }
 
+TEST(FilterIteratorTest, Lambda) {
+  auto IsOdd = [](int a) { return a % 2 == 1; };
+  int a[] = {0, 1, 2, 3, 4, 5, 6};
+  const auto Range = make_filter_range(make_range(a, a + 7), IsOdd);
+  ASSERT_EQ(3, std::distance(Range.begin(), Range.end()));
+  SmallVector<int, 3> Actual(Range.begin(), Range.end());
+  EXPECT_EQ((SmallVector<int, 3>{1, 3, 5}), Actual);
+}
+
+TEST(FilterIteratorTest, StdFunction) {
+  std::function<bool(int)> IsOdd = [](int a) { return a % 2 == 1; };
+  int a[] = {0, 1, 2, 3, 4, 5, 6};
+  const auto Range = make_filter_range(make_range(a, a + 7), IsOdd);
+  ASSERT_EQ(3, std::distance(Range.begin(), Range.end()));
+  SmallVector<int, 3> Actual(Range.begin(), Range.end());
+  EXPECT_EQ((SmallVector<int, 3>{1, 3, 5}), Actual);
+}
+
+TEST(FilterIteratorTest, FunctionPointer) {
+  bool (*IsOdd)(int) = [](int a) { return a % 2 == 1; };
+  int a[] = {0, 1, 2, 3, 4, 5, 6};
+  const auto Range = make_filter_range(make_range(a, a + 7), IsOdd);
+  ASSERT_EQ(3, std::distance(Range.begin(), Range.end()));
+  SmallVector<int, 3> Actual(Range.begin(), Range.end());
+  EXPECT_EQ((SmallVector<int, 3>{1, 3, 5}), Actual);
+}
+
+TEST(FilterIteratorTest, Composition) {
+  const auto IsOdd = [](int a) { return a % 2 == 1; };
+  std::unique_ptr<int> a[] = {make_unique<int>(0), make_unique<int>(1),
+                              make_unique<int>(2), make_unique<int>(3),
+                              make_unique<int>(4), make_unique<int>(5),
+                              make_unique<int>(6)};
+  using PointeeIterator = pointee_iterator<std::unique_ptr<int> *>;
+  const auto Range = make_filter_range(
+      make_range(PointeeIterator(a), PointeeIterator(a + 7)), IsOdd);
+  ASSERT_EQ(3, std::distance(Range.begin(), Range.end()));
+  SmallVector<int, 3> Actual(Range.begin(), Range.end());
+  EXPECT_EQ((SmallVector<int, 3>{1, 3, 5}), Actual);
+}
+
+TEST(FilterIteratorTest, InputIterator) {
+  struct InputIterator
+      : iterator_adaptor_base<InputIterator, int *, std::input_iterator_tag> {
+    using BaseT =
+        iterator_adaptor_base<InputIterator, int *, std::input_iterator_tag>;
+
+    InputIterator(int *It) : BaseT(It) {}
+  };
+
+  auto IsOdd = [](int a) { return a % 2 == 1; };
+  int a[] = {0, 1, 2, 3, 4, 5, 6};
+  const auto Range = make_filter_range(
+      make_range(InputIterator(a), InputIterator(a + 7)), IsOdd);
+  SmallVector<int, 3> Actual(Range.begin(), Range.end());
+  EXPECT_EQ((SmallVector<int, 3>{1, 3, 5}), Actual);
+}
+
+TEST(FilterIteratorTest, Decrement) {
+  auto IsOdd = [](int a) { return a % 2 == 1; };
+  int a[] = {0, 1, 2, 3, 4, 5, 6};
+  auto Iter = make_filter_range(make_range(a, a + 7), IsOdd).begin();
+  EXPECT_EQ(1, *Iter);
+  ++Iter;
+  EXPECT_EQ(3, *Iter);
+  --Iter;
+  EXPECT_EQ(1, *Iter);
+  std::advance(Iter, 2);
+  EXPECT_EQ(5, *Iter);
+  --Iter;
+  EXPECT_EQ(3, *Iter);
+}
+
 } // anonymous namespace