diff --git a/llvm/include/llvm/ADT/STLExtras.h b/llvm/include/llvm/ADT/STLExtras.h
--- a/llvm/include/llvm/ADT/STLExtras.h
+++ b/llvm/include/llvm/ADT/STLExtras.h
@@ -26,6 +26,7 @@
 #include "llvm/Config/abi-breaking.h"
 #include "llvm/Support/ErrorHandling.h"
 #include <algorithm>
+#include <bits/utility.h>
 #include <cassert>
 #include <cstddef>
 #include <cstdint>
@@ -856,33 +857,70 @@
   }
 };
 
+/// Helper to obtain the iterator types for the tuple storage within `zippy`.
+template <template <typename...> class ItType, typename TupleStorageType,
+          typename IndexSequence>
+struct ZippyIteratorTuple;
+
+/// Partial specialization for non-const tuple storage.
+template <template <typename...> class ItType, typename... Args,
+          std::size_t... Ns>
+struct ZippyIteratorTuple<ItType, std::tuple<Args...>,
+                          std::index_sequence<Ns...>> {
+  using type = ItType<decltype(adl_begin(
+      std::get<Ns>(declval<std::tuple<Args...> &>())))...>;
+};
+
+/// Partial specialization for const tuple storage.
+template <template <typename...> class ItType, typename... Args,
+          std::size_t... Ns>
+struct ZippyIteratorTuple<ItType, const std::tuple<Args...>,
+                          std::index_sequence<Ns...>> {
+  using type = ItType<decltype(adl_begin(
+      std::get<Ns>(declval<const std::tuple<Args...> &>())))...>;
+};
+
 template <template <typename...> class ItType, typename... Args> class zippy {
+private:
+  std::tuple<Args...> storage;
+  using IndexSequence = std::index_sequence_for<Args...>;
+
 public:
-  using iterator = ItType<decltype(std::begin(std::declval<Args>()))...>;
+  using iterator = typename ZippyIteratorTuple<ItType, decltype(storage),
+                                               IndexSequence>::type;
+  using const_iterator =
+      typename ZippyIteratorTuple<ItType, const decltype(storage),
+                                  IndexSequence>::type;
   using iterator_category = typename iterator::iterator_category;
   using value_type = typename iterator::value_type;
   using difference_type = typename iterator::difference_type;
   using pointer = typename iterator::pointer;
   using reference = typename iterator::reference;
+  using const_reference = typename const_iterator::reference;
 
-private:
-  std::tuple<Args...> ts;
+  zippy(Args &&...args) : storage(std::forward<Args>(args)...) {}
 
+  const_iterator begin() const { return begin_impl(IndexSequence{}); }
+  iterator begin() { return begin_impl(IndexSequence{}); }
+  const_iterator end() const { return end_impl(IndexSequence{}); }
+  iterator end() { return end_impl(IndexSequence{}); }
+
+private:
   template <size_t... Ns>
-  iterator begin_impl(std::index_sequence<Ns...>) const {
-    return iterator(std::begin(std::get<Ns>(ts))...);
+  const_iterator begin_impl(std::index_sequence<Ns...>) const {
+    return const_iterator(adl_begin(std::get<Ns>(storage))...);
   }
-  template <size_t... Ns> iterator end_impl(std::index_sequence<Ns...>) const {
-    return iterator(std::end(std::get<Ns>(ts))...);
+  template <size_t... Ns> iterator begin_impl(std::index_sequence<Ns...>) {
+    return iterator(adl_begin(std::get<Ns>(storage))...);
   }
 
-public:
-  zippy(Args &&... ts_) : ts(std::forward<Args>(ts_)...) {}
-
-  iterator begin() const {
-    return begin_impl(std::index_sequence_for<Args...>{});
+  template <size_t... Ns>
+  const_iterator end_impl(std::index_sequence<Ns...>) const {
+    return const_iterator(adl_end(std::get<Ns>(storage))...);
+  }
+  template <size_t... Ns> iterator end_impl(std::index_sequence<Ns...>) {
+    return iterator(adl_end(std::get<Ns>(storage))...);
   }
-  iterator end() const { return end_impl(std::index_sequence_for<Args...>{}); }
 };
 
 } // end namespace detail
diff --git a/llvm/unittests/ADT/IteratorTest.cpp b/llvm/unittests/ADT/IteratorTest.cpp
--- a/llvm/unittests/ADT/IteratorTest.cpp
+++ b/llvm/unittests/ADT/IteratorTest.cpp
@@ -6,15 +6,18 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "llvm/ADT/ilist.h"
 #include "llvm/ADT/iterator.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/ilist.h"
+#include "gmock/gmock.h"
 #include "gtest/gtest.h"
+#include <iterator>
 #include <optional>
 
 using namespace llvm;
+using testing::ElementsAre;
 
 namespace {
 
@@ -430,6 +433,96 @@
   EXPECT_EQ(iters, 6u);
 }
 
+template <typename T> bool IsConstRef(const T &) { return true; }
+template <typename T> bool IsConstRef(T &) { return false; }
+
+bool IsBoolConstRef(std::vector<bool>::reference) { return false; }
+bool IsBoolConstRef(std::vector<bool>::const_reference) { return true; }
+
+template <typename T> const T &MakeConst(const T &value) { return value; }
+
+TEST(ZipIteratorTest, ZipEqualConstCorrectness) {
+  const std::vector<unsigned> c_first = {3, 1, 4};
+  std::vector<unsigned> first = c_first;
+  const SmallVector<bool> c_second = {1, 1, 0};
+  SmallVector<bool> second = c_second;
+
+  for (auto [a, b, c, d] : zip_equal(c_first, first, c_second, second)) {
+    b = 0;
+    d = true;
+    EXPECT_TRUE(IsConstRef(a));
+    EXPECT_FALSE(IsConstRef(b));
+    EXPECT_TRUE(IsConstRef(c));
+    EXPECT_FALSE(IsConstRef(d));
+  }
+
+  EXPECT_THAT(first, ElementsAre(0, 0, 0));
+  EXPECT_THAT(second, ElementsAre(true, true, true));
+
+  std::vector<bool> nemesis = {true, false, true};
+  const std::vector<bool> c_nemesis = nemesis;
+
+  for (auto &&[a, b, c, d] : zip_equal(first, c_first, nemesis, c_nemesis)) {
+    a = 2;
+    c = true;
+    EXPECT_FALSE(IsConstRef(a));
+    EXPECT_TRUE(IsConstRef(b));
+    EXPECT_FALSE(IsBoolConstRef(c));
+    EXPECT_TRUE(IsBoolConstRef(d));
+  }
+
+  EXPECT_THAT(first, ElementsAre(2, 2, 2));
+  EXPECT_THAT(nemesis, ElementsAre(true, true, true));
+
+  unsigned iters = 0;
+  for (const auto &[a, b, c, d] :
+       zip_equal(first, c_first, nemesis, c_nemesis)) {
+    EXPECT_FALSE(IsConstRef(a));
+    EXPECT_TRUE(IsConstRef(b));
+    EXPECT_FALSE(IsBoolConstRef(c));
+    EXPECT_TRUE(IsBoolConstRef(d));
+    ++iters;
+  }
+  EXPECT_EQ(iters, 3u);
+  iters = 0;
+
+  for (const auto &[a, b, c, d] :
+       MakeConst(zip_equal(first, c_first, nemesis, c_nemesis))) {
+    EXPECT_FALSE(IsConstRef(a));
+    EXPECT_TRUE(IsConstRef(b));
+    EXPECT_FALSE(IsBoolConstRef(c));
+    EXPECT_TRUE(IsBoolConstRef(d));
+    ++iters;
+  }
+  EXPECT_EQ(iters, 3u);
+}
+
+TEST(ZipIteratorTest, ZipEqualTemporaries) {
+  unsigned iters = 0;
+  for (auto [a, b, c] : zip_equal(SmallVector<int>{1, 2, 3}, std::string("abc"),
+                                  std::vector<bool>{true, false, true})) {
+    a = 3;
+    b = 'c';
+    c = false;
+    EXPECT_FALSE(IsConstRef(a));
+    EXPECT_FALSE(IsConstRef(b));
+    EXPECT_FALSE(IsBoolConstRef(c));
+    ++iters;
+  }
+  EXPECT_EQ(iters, 3u);
+  iters = 0;
+
+  for (auto [a, b, c] :
+       MakeConst(zip_equal(SmallVector<int>{1, 2, 3}, std::string("abc"),
+                           std::vector<bool>{true, false, true}))) {
+    EXPECT_TRUE(IsConstRef(a));
+    EXPECT_TRUE(IsConstRef(b));
+    EXPECT_TRUE(IsBoolConstRef(c));
+    ++iters;
+  }
+  EXPECT_EQ(iters, 3u);
+}
+
 #if !defined(NDEBUG) && GTEST_HAS_DEATH_TEST
 // Check that an assertion is triggered when ranges passed to `zip_equal` differ
 // in length.