diff --git a/libcxx/include/__algorithm/inplace_merge.h b/libcxx/include/__algorithm/inplace_merge.h
index eb3c0bdbc2db..a6bcc66a2fa4 100644
--- a/libcxx/include/__algorithm/inplace_merge.h
+++ b/libcxx/include/__algorithm/inplace_merge.h
@@ -114,8 +114,8 @@ _LIBCPP_HIDE_FROM_ABI void __buffered_inplace_merge(
     for (_BidirectionalIterator __i = __middle; __i != __last;
          __d.template __incr<value_type>(), (void)++__i, (void)++__p)
       ::new ((void*)__p) value_type(_IterOps<_AlgPolicy>::__iter_move(__i));
-    typedef __unconstrained_reverse_iterator<_BidirectionalIterator> _RBi;
-    typedef __unconstrained_reverse_iterator<value_type*> _Rv;
+    typedef reverse_iterator<_BidirectionalIterator> _RBi;
+    typedef reverse_iterator<value_type*> _Rv;
     typedef __invert<_Compare> _Inverted;
     std::__half_inplace_merge<_AlgPolicy>(
         _Rv(__p), _Rv(__buff), _RBi(__middle), _RBi(__first), _RBi(__last), _Inverted(__comp));
diff --git a/libcxx/include/__iterator/reverse_iterator.h b/libcxx/include/__iterator/reverse_iterator.h
index 9aab96866f4f..2ae146193485 100644
--- a/libcxx/include/__iterator/reverse_iterator.h
+++ b/libcxx/include/__iterator/reverse_iterator.h
@@ -316,172 +316,6 @@ inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 reverse_iterator<_Ite
 }
 #endif
 
-#if _LIBCPP_STD_VER <= 17
-template <class _Iter>
-using __unconstrained_reverse_iterator = reverse_iterator<_Iter>;
-#else
-
-// __unconstrained_reverse_iterator allows us to use reverse iterators in the implementation of algorithms by working
-// around a language issue in C++20.
-// In C++20, when a reverse iterator wraps certain C++20-hostile iterators, calling comparison operators on it will
-// result in a compilation error. However, calling comparison operators on the pristine hostile iterator is not
-// an error. Thus, we cannot use reverse_iterators in the implementation of an algorithm that accepts a
-// C++20-hostile iterator. This class is an internal workaround -- it is a copy of reverse_iterator with
-// tweaks to make it support hostile iterators.
-//
-// A C++20-hostile iterator is one that defines a comparison operator where one of the arguments is an exact match
-// and the other requires an implicit conversion, for example:
-//   friend bool operator==(const BaseIter&, const DerivedIter&);
-//
-// C++20 rules for rewriting equality operators create another overload of this function with parameters reversed:
-//   friend bool operator==(const DerivedIter&, const BaseIter&);
-//
-// This creates an ambiguity in overload resolution.
-//
-// Clang treats this ambiguity differently in different contexts. When operator== is actually called in the function
-// body, the code is accepted with a warning. When a concept requires operator== to be a valid expression, however,
-// it evaluates to false. Thus, the implementation of reverse_iterator::operator== can actually call operator== on its
-// base iterators, but the constraints on reverse_iterator::operator== prevent it from being considered during overload
-// resolution. This class simply removes the problematic constraints from comparison functions.
-template <class _Iter>
-class __unconstrained_reverse_iterator {
-  _Iter __iter_;
-
-public:
-  static_assert(__has_bidirectional_iterator_category<_Iter>::value || bidirectional_iterator<_Iter>);
-
-  using iterator_type = _Iter;
-  using iterator_category =
-      _If<__has_random_access_iterator_category<_Iter>::value,
-          random_access_iterator_tag,
-          __iterator_category_type<_Iter>>;
-  using pointer         = __iterator_pointer_type<_Iter>;
-  using value_type      = iter_value_t<_Iter>;
-  using difference_type = iter_difference_t<_Iter>;
-  using reference       = iter_reference_t<_Iter>;
-
-  _LIBCPP_HIDE_FROM_ABI constexpr __unconstrained_reverse_iterator()                                        = default;
-  _LIBCPP_HIDE_FROM_ABI constexpr __unconstrained_reverse_iterator(const __unconstrained_reverse_iterator&) = default;
-  _LIBCPP_HIDE_FROM_ABI constexpr explicit __unconstrained_reverse_iterator(_Iter __iter) : __iter_(__iter) {}
-
-  _LIBCPP_HIDE_FROM_ABI constexpr _Iter base() const { return __iter_; }
-  _LIBCPP_HIDE_FROM_ABI constexpr reference operator*() const {
-    auto __tmp = __iter_;
-    return *--__tmp;
-  }
-
-  _LIBCPP_HIDE_FROM_ABI constexpr pointer operator->() const {
-    if constexpr (is_pointer_v<_Iter>) {
-      return std::prev(__iter_);
-    } else {
-      return std::prev(__iter_).operator->();
-    }
-  }
-
-  _LIBCPP_HIDE_FROM_ABI friend constexpr iter_rvalue_reference_t<_Iter>
-  iter_move(const __unconstrained_reverse_iterator& __i) noexcept(
-      is_nothrow_copy_constructible_v<_Iter>&& noexcept(ranges::iter_move(--std::declval<_Iter&>()))) {
-    auto __tmp = __i.base();
-    return ranges::iter_move(--__tmp);
-  }
-
-  _LIBCPP_HIDE_FROM_ABI constexpr __unconstrained_reverse_iterator& operator++() {
-    --__iter_;
-    return *this;
-  }
-
-  _LIBCPP_HIDE_FROM_ABI constexpr __unconstrained_reverse_iterator operator++(int) {
-    auto __tmp = *this;
-    --__iter_;
-    return __tmp;
-  }
-
-  _LIBCPP_HIDE_FROM_ABI constexpr __unconstrained_reverse_iterator& operator--() {
-    ++__iter_;
-    return *this;
-  }
-
-  _LIBCPP_HIDE_FROM_ABI constexpr __unconstrained_reverse_iterator operator--(int) {
-    auto __tmp = *this;
-    ++__iter_;
-    return __tmp;
-  }
-
-  _LIBCPP_HIDE_FROM_ABI constexpr __unconstrained_reverse_iterator& operator+=(difference_type __n) {
-    __iter_ -= __n;
-    return *this;
-  }
-
-  _LIBCPP_HIDE_FROM_ABI constexpr __unconstrained_reverse_iterator& operator-=(difference_type __n) {
-    __iter_ += __n;
-    return *this;
-  }
-
-  _LIBCPP_HIDE_FROM_ABI constexpr __unconstrained_reverse_iterator operator+(difference_type __n) const {
-    return __unconstrained_reverse_iterator(__iter_ - __n);
-  }
-
-  _LIBCPP_HIDE_FROM_ABI constexpr __unconstrained_reverse_iterator operator-(difference_type __n) const {
-    return __unconstrained_reverse_iterator(__iter_ + __n);
-  }
-
-  _LIBCPP_HIDE_FROM_ABI constexpr difference_type operator-(const __unconstrained_reverse_iterator& __other) const {
-    return __other.__iter_ - __iter_;
-  }
-
-  _LIBCPP_HIDE_FROM_ABI constexpr auto operator[](difference_type __n) const { return *(*this + __n); }
-
-  // Deliberately unconstrained unlike the comparison functions in `reverse_iterator` -- see the class comment for the
-  // rationale.
-  _LIBCPP_HIDE_FROM_ABI friend constexpr bool
-  operator==(const __unconstrained_reverse_iterator& __lhs, const __unconstrained_reverse_iterator& __rhs) {
-    return __lhs.base() == __rhs.base();
-  }
-
-  _LIBCPP_HIDE_FROM_ABI friend constexpr bool
-  operator!=(const __unconstrained_reverse_iterator& __lhs, const __unconstrained_reverse_iterator& __rhs) {
-    return __lhs.base() != __rhs.base();
-  }
-
-  _LIBCPP_HIDE_FROM_ABI friend constexpr bool
-  operator<(const __unconstrained_reverse_iterator& __lhs, const __unconstrained_reverse_iterator& __rhs) {
-    return __lhs.base() > __rhs.base();
-  }
-
-  _LIBCPP_HIDE_FROM_ABI friend constexpr bool
-  operator>(const __unconstrained_reverse_iterator& __lhs, const __unconstrained_reverse_iterator& __rhs) {
-    return __lhs.base() < __rhs.base();
-  }
-
-  _LIBCPP_HIDE_FROM_ABI friend constexpr bool
-  operator<=(const __unconstrained_reverse_iterator& __lhs, const __unconstrained_reverse_iterator& __rhs) {
-    return __lhs.base() >= __rhs.base();
-  }
-
-  _LIBCPP_HIDE_FROM_ABI friend constexpr bool
-  operator>=(const __unconstrained_reverse_iterator& __lhs, const __unconstrained_reverse_iterator& __rhs) {
-    return __lhs.base() <= __rhs.base();
-  }
-};
-
-#endif // _LIBCPP_STD_VER <= 17
-
-template <template <class> class _RevIter1, template <class> class _RevIter2, class _Iter>
-struct __unwrap_reverse_iter_impl {
-  using _UnwrappedIter  = decltype(__unwrap_iter_impl<_Iter>::__unwrap(std::declval<_Iter>()));
-  using _ReverseWrapper = _RevIter1<_RevIter2<_Iter> >;
-
-  static _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _ReverseWrapper
-  __rewrap(_ReverseWrapper __orig_iter, _UnwrappedIter __unwrapped_iter) {
-    return _ReverseWrapper(
-        _RevIter2<_Iter>(__unwrap_iter_impl<_Iter>::__rewrap(__orig_iter.base().base(), __unwrapped_iter)));
-  }
-
-  static _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _UnwrappedIter __unwrap(_ReverseWrapper __i) _NOEXCEPT {
-    return __unwrap_iter_impl<_Iter>::__unwrap(__i.base().base());
-  }
-};
-
 #if _LIBCPP_STD_VER >= 20
 template <ranges::bidirectional_range _Range>
 _LIBCPP_HIDE_FROM_ABI constexpr ranges::subrange<reverse_iterator<ranges::iterator_t<_Range>>,
@@ -493,24 +327,20 @@ __reverse_range(_Range&& __range) {
 #endif
 
 template <class _Iter, bool __b>
-struct __unwrap_iter_impl<reverse_iterator<reverse_iterator<_Iter> >, __b>
-    : __unwrap_reverse_iter_impl<reverse_iterator, reverse_iterator, _Iter> {};
+struct __unwrap_iter_impl<reverse_iterator<reverse_iterator<_Iter> >, __b> {
+  using _UnwrappedIter  = decltype(__unwrap_iter_impl<_Iter>::__unwrap(std::declval<_Iter>()));
+  using _ReverseWrapper = reverse_iterator<reverse_iterator<_Iter> >;
 
-#if _LIBCPP_STD_VER >= 20
+  static _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _ReverseWrapper
+  __rewrap(_ReverseWrapper __orig_iter, _UnwrappedIter __unwrapped_iter) {
+    return _ReverseWrapper(
+        reverse_iterator<_Iter>(__unwrap_iter_impl<_Iter>::__rewrap(__orig_iter.base().base(), __unwrapped_iter)));
+  }
 
-template <class _Iter, bool __b>
-struct __unwrap_iter_impl<reverse_iterator<__unconstrained_reverse_iterator<_Iter>>, __b>
-    : __unwrap_reverse_iter_impl<reverse_iterator, __unconstrained_reverse_iterator, _Iter> {};
-
-template <class _Iter, bool __b>
-struct __unwrap_iter_impl<__unconstrained_reverse_iterator<reverse_iterator<_Iter>>, __b>
-    : __unwrap_reverse_iter_impl<__unconstrained_reverse_iterator, reverse_iterator, _Iter> {};
-
-template <class _Iter, bool __b>
-struct __unwrap_iter_impl<__unconstrained_reverse_iterator<__unconstrained_reverse_iterator<_Iter>>, __b>
-    : __unwrap_reverse_iter_impl<__unconstrained_reverse_iterator, __unconstrained_reverse_iterator, _Iter> {};
-
-#endif // _LIBCPP_STD_VER >= 20
+  static _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _UnwrappedIter __unwrap(_ReverseWrapper __i) _NOEXCEPT {
+    return __unwrap_iter_impl<_Iter>::__unwrap(__i.base().base());
+  }
+};
 
 _LIBCPP_END_NAMESPACE_STD
 
diff --git a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.cmp/equal.pass.cpp b/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.cmp/equal.pass.cpp
deleted file mode 100644
index 583e733c07cb..000000000000
--- a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.cmp/equal.pass.cpp
+++ /dev/null
@@ -1,47 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-// <iterator>
-
-// __unconstrained_reverse_iterator
-
-// template <BidirectionalIterator Iter1, BidirectionalIterator Iter2>
-//   requires HasEqualTo<Iter1, Iter2>
-// bool operator==(const __unconstrained_reverse_iterator<Iter1>& x, const __unconstrained_reverse_iterator<Iter2>& y); // constexpr since C++17
-
-#include <iterator>
-#include <cassert>
-
-#include "test_macros.h"
-#include "test_iterators.h"
-
-template <class It>
-TEST_CONSTEXPR_CXX17 void test(It l, It r, bool x) {
-    const std::__unconstrained_reverse_iterator<It> r1(l);
-    const std::__unconstrained_reverse_iterator<It> r2(r);
-    assert((r1 == r2) == x);
-}
-
-TEST_CONSTEXPR_CXX17 bool tests() {
-    const char* s = "1234567890";
-    test(bidirectional_iterator<const char*>(s), bidirectional_iterator<const char*>(s), true);
-    test(bidirectional_iterator<const char*>(s), bidirectional_iterator<const char*>(s+1), false);
-    test(random_access_iterator<const char*>(s), random_access_iterator<const char*>(s), true);
-    test(random_access_iterator<const char*>(s), random_access_iterator<const char*>(s+1), false);
-    test(s, s, true);
-    test(s, s+1, false);
-    return true;
-}
-
-int main(int, char**) {
-    tests();
-#if TEST_STD_VER > 14
-    static_assert(tests(), "");
-#endif
-    return 0;
-}
diff --git a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.cmp/greater-equal.pass.cpp b/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.cmp/greater-equal.pass.cpp
deleted file mode 100644
index 9e908418d075..000000000000
--- a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.cmp/greater-equal.pass.cpp
+++ /dev/null
@@ -1,47 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-// <iterator>
-
-// __unconstrained_reverse_iterator
-
-// template <RandomAccessIterator Iter1, RandomAccessIterator Iter2>
-//   requires HasGreater<Iter1, Iter2>
-// bool operator>=(const __unconstrained_reverse_iterator<Iter1>& x, const __unconstrained_reverse_iterator<Iter2>& y); // constexpr since C++17
-
-#include <iterator>
-#include <cassert>
-
-#include "test_macros.h"
-#include "test_iterators.h"
-
-template <class It>
-TEST_CONSTEXPR_CXX17 void test(It l, It r, bool x) {
-    const std::__unconstrained_reverse_iterator<It> r1(l);
-    const std::__unconstrained_reverse_iterator<It> r2(r);
-    assert((r1 >= r2) == x);
-}
-
-TEST_CONSTEXPR_CXX17 bool tests() {
-    const char* s = "1234567890";
-    test(random_access_iterator<const char*>(s), random_access_iterator<const char*>(s), true);
-    test(random_access_iterator<const char*>(s), random_access_iterator<const char*>(s+1), true);
-    test(random_access_iterator<const char*>(s+1), random_access_iterator<const char*>(s), false);
-    test(s, s, true);
-    test(s, s+1, true);
-    test(s+1, s, false);
-    return true;
-}
-
-int main(int, char**) {
-    tests();
-#if TEST_STD_VER > 14
-    static_assert(tests(), "");
-#endif
-    return 0;
-}
diff --git a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.cmp/greater.pass.cpp b/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.cmp/greater.pass.cpp
deleted file mode 100644
index f1afd23bab13..000000000000
--- a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.cmp/greater.pass.cpp
+++ /dev/null
@@ -1,47 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-// <iterator>
-
-// __unconstrained_reverse_iterator
-
-// template <RandomAccessIterator Iter1, RandomAccessIterator Iter2>
-//   requires HasGreater<Iter1, Iter2>
-// bool operator>(const __unconstrained_reverse_iterator<Iter1>& x, const __unconstrained_reverse_iterator<Iter2>& y); // constexpr in C++17
-
-#include <iterator>
-#include <cassert>
-
-#include "test_macros.h"
-#include "test_iterators.h"
-
-template <class It>
-TEST_CONSTEXPR_CXX17 void test(It l, It r, bool x) {
-    const std::__unconstrained_reverse_iterator<It> r1(l);
-    const std::__unconstrained_reverse_iterator<It> r2(r);
-    assert((r1 > r2) == x);
-}
-
-TEST_CONSTEXPR_CXX17 bool tests() {
-    const char* s = "1234567890";
-    test(random_access_iterator<const char*>(s), random_access_iterator<const char*>(s), false);
-    test(random_access_iterator<const char*>(s), random_access_iterator<const char*>(s+1), true);
-    test(random_access_iterator<const char*>(s+1), random_access_iterator<const char*>(s), false);
-    test(s, s, false);
-    test(s, s+1, true);
-    test(s+1, s, false);
-    return true;
-}
-
-int main(int, char**) {
-    tests();
-#if TEST_STD_VER > 14
-    static_assert(tests(), "");
-#endif
-    return 0;
-}
diff --git a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.cmp/less-equal.pass.cpp b/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.cmp/less-equal.pass.cpp
deleted file mode 100644
index c710212308fa..000000000000
--- a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.cmp/less-equal.pass.cpp
+++ /dev/null
@@ -1,47 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-// <iterator>
-
-// __unconstrained_reverse_iterator
-
-// template <RandomAccessIterator Iter1, RandomAccessIterator Iter2>
-//   requires HasGreater<Iter1, Iter2>
-// bool operator<=(const __unconstrained_reverse_iterator<Iter1>& x, const __unconstrained_reverse_iterator<Iter2>& y); // constexpr in C++17
-
-#include <iterator>
-#include <cassert>
-
-#include "test_macros.h"
-#include "test_iterators.h"
-
-template <class It>
-TEST_CONSTEXPR_CXX17 void test(It l, It r, bool x) {
-    const std::__unconstrained_reverse_iterator<It> r1(l);
-    const std::__unconstrained_reverse_iterator<It> r2(r);
-    assert((r1 <= r2) == x);
-}
-
-TEST_CONSTEXPR_CXX17 bool tests() {
-    const char* s = "1234567890";
-    test(random_access_iterator<const char*>(s), random_access_iterator<const char*>(s), true);
-    test(random_access_iterator<const char*>(s), random_access_iterator<const char*>(s+1), false);
-    test(random_access_iterator<const char*>(s+1), random_access_iterator<const char*>(s), true);
-    test(s, s, true);
-    test(s, s+1, false);
-    test(s+1, s, true);
-    return true;
-}
-
-int main(int, char**) {
-    tests();
-#if TEST_STD_VER > 14
-    static_assert(tests(), "");
-#endif
-    return 0;
-}
diff --git a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.cmp/less.pass.cpp b/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.cmp/less.pass.cpp
deleted file mode 100644
index ffd3a0323373..000000000000
--- a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.cmp/less.pass.cpp
+++ /dev/null
@@ -1,47 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-// <iterator>
-
-// __unconstrained_reverse_iterator
-
-// template <RandomAccessIterator Iter1, RandomAccessIterator Iter2>
-//   requires HasGreater<Iter1, Iter2>
-// bool operator<(const __unconstrained_reverse_iterator<Iter1>& x, const __unconstrained_reverse_iterator<Iter2>& y); // constexpr in C++17
-
-#include <iterator>
-#include <cassert>
-
-#include "test_macros.h"
-#include "test_iterators.h"
-
-template <class It>
-TEST_CONSTEXPR_CXX17 void test(It l, It r, bool x) {
-    const std::__unconstrained_reverse_iterator<It> r1(l);
-    const std::__unconstrained_reverse_iterator<It> r2(r);
-    assert((r1 < r2) == x);
-}
-
-TEST_CONSTEXPR_CXX17 bool tests() {
-    const char* s = "1234567890";
-    test(random_access_iterator<const char*>(s), random_access_iterator<const char*>(s), false);
-    test(random_access_iterator<const char*>(s), random_access_iterator<const char*>(s+1), false);
-    test(random_access_iterator<const char*>(s+1), random_access_iterator<const char*>(s), true);
-    test(s, s, false);
-    test(s, s+1, false);
-    test(s+1, s, true);
-    return true;
-}
-
-int main(int, char**) {
-    tests();
-#if TEST_STD_VER > 14
-    static_assert(tests(), "");
-#endif
-    return 0;
-}
diff --git a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.cmp/not-equal.pass.cpp b/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.cmp/not-equal.pass.cpp
deleted file mode 100644
index 614f159cc805..000000000000
--- a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.cmp/not-equal.pass.cpp
+++ /dev/null
@@ -1,47 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-// <iterator>
-
-// __unconstrained_reverse_iterator
-
-// template <BidirectionalIterator Iter1, BidirectionalIterator Iter2>
-//   requires HasEqualTo<Iter1, Iter2>
-// bool operator!=(const __unconstrained_reverse_iterator<Iter1>& x, const __unconstrained_reverse_iterator<Iter2>& y); // constexpr in C++17
-
-#include <iterator>
-#include <cassert>
-
-#include "test_macros.h"
-#include "test_iterators.h"
-
-template <class It>
-TEST_CONSTEXPR_CXX17 void test(It l, It r, bool x) {
-    const std::__unconstrained_reverse_iterator<It> r1(l);
-    const std::__unconstrained_reverse_iterator<It> r2(r);
-    assert((r1 != r2) == x);
-}
-
-TEST_CONSTEXPR_CXX17 bool tests() {
-    const char* s = "1234567890";
-    test(bidirectional_iterator<const char*>(s), bidirectional_iterator<const char*>(s), false);
-    test(bidirectional_iterator<const char*>(s), bidirectional_iterator<const char*>(s+1), true);
-    test(random_access_iterator<const char*>(s), random_access_iterator<const char*>(s), false);
-    test(random_access_iterator<const char*>(s), random_access_iterator<const char*>(s+1), true);
-    test(s, s, false);
-    test(s, s+1, true);
-    return true;
-}
-
-int main(int, char**) {
-    tests();
-#if TEST_STD_VER > 14
-    static_assert(tests(), "");
-#endif
-    return 0;
-}
diff --git a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.cons/assign.LWG3435.verify.cpp b/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.cons/assign.LWG3435.verify.cpp
deleted file mode 100644
index 835e2b65c19c..000000000000
--- a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.cons/assign.LWG3435.verify.cpp
+++ /dev/null
@@ -1,26 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-// <iterator>
-
-// __unconstrained_reverse_iterator
-
-// template <class U>
-//  requires !same_as<U, Iter> && convertible_to<const U&, Iter> && assignable_from<Iter&, const U&>
-// __unconstrained_reverse_iterator& operator=(const __unconstrained_reverse_iterator<U>& u);
-
-#include <iterator>
-
-struct Base { };
-struct Derived : Base { };
-
-void test() {
-    std::__unconstrained_reverse_iterator<Base*> base;
-    std::__unconstrained_reverse_iterator<Derived*> derived;
-    derived = base; // expected-error {{no viable overloaded '='}}
-}
diff --git a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.cons/ctor.default.pass.cpp b/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.cons/ctor.default.pass.cpp
deleted file mode 100644
index 66972d7243cc..000000000000
--- a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.cons/ctor.default.pass.cpp
+++ /dev/null
@@ -1,40 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-// <iterator>
-
-// __unconstrained_reverse_iterator
-
-// __unconstrained_reverse_iterator(); // constexpr since C++17
-
-#include <iterator>
-
-#include "test_macros.h"
-#include "test_iterators.h"
-
-template <class It>
-TEST_CONSTEXPR_CXX17 void test() {
-    std::__unconstrained_reverse_iterator<It> r;
-    (void)r;
-}
-
-TEST_CONSTEXPR_CXX17 bool tests() {
-    test<bidirectional_iterator<const char*> >();
-    test<random_access_iterator<char*> >();
-    test<char*>();
-    test<const char*>();
-    return true;
-}
-
-int main(int, char**) {
-    tests();
-#if TEST_STD_VER > 14
-    static_assert(tests(), "");
-#endif
-    return 0;
-}
diff --git a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.cons/ctor.iter.explicit.verify.cpp b/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.cons/ctor.iter.explicit.verify.cpp
deleted file mode 100644
index 6440e284f6a0..000000000000
--- a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.cons/ctor.iter.explicit.verify.cpp
+++ /dev/null
@@ -1,22 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-// <iterator>
-
-// __unconstrained_reverse_iterator
-
-// explicit __unconstrained_reverse_iterator(Iter x);
-
-// test explicitness
-
-#include <iterator>
-
-void f() {
-    char const* it = "";
-    std::__unconstrained_reverse_iterator<char const*> r = it; // expected-error{{no viable conversion from 'const char *' to 'std::__unconstrained_reverse_iterator<const char *>'}}
-}
diff --git a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.cons/ctor.iter.pass.cpp b/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.cons/ctor.iter.pass.cpp
deleted file mode 100644
index e4d0874d50b5..000000000000
--- a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.cons/ctor.iter.pass.cpp
+++ /dev/null
@@ -1,41 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-// <iterator>
-
-// __unconstrained_reverse_iterator
-
-// explicit __unconstrained_reverse_iterator(Iter x); // constexpr since C++17
-
-#include <iterator>
-#include <cassert>
-
-#include "test_macros.h"
-#include "test_iterators.h"
-
-template <class It>
-TEST_CONSTEXPR_CXX17 void test(It i) {
-    std::__unconstrained_reverse_iterator<It> r(i);
-    assert(r.base() == i);
-}
-
-TEST_CONSTEXPR_CXX17 bool tests() {
-    const char s[] = "123";
-    test(bidirectional_iterator<const char*>(s));
-    test(random_access_iterator<const char*>(s));
-    test(s);
-    return true;
-}
-
-int main(int, char**) {
-    tests();
-#if TEST_STD_VER > 14
-    static_assert(tests(), "");
-#endif
-    return 0;
-}
diff --git a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.cons/ctor.reverse_iterator.LWG3435.verify.cpp b/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.cons/ctor.reverse_iterator.LWG3435.verify.cpp
deleted file mode 100644
index 7ea4a61ce660..000000000000
--- a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.cons/ctor.reverse_iterator.LWG3435.verify.cpp
+++ /dev/null
@@ -1,25 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-// <iterator>
-
-// __unconstrained_reverse_iterator
-
-// template <class U>
-//  requires !same_as<U, Iter> && convertible_to<const U&, Iter>
-// __unconstrained_reverse_iterator(const __unconstrained_reverse_iterator<U> &);
-
-#include <iterator>
-
-struct Base { };
-struct Derived : Base { };
-
-void test() {
-    std::__unconstrained_reverse_iterator<Base*> base;
-    std::__unconstrained_reverse_iterator<Derived*> derived(base); // expected-error {{no matching constructor for initialization of 'std::__unconstrained_reverse_iterator<Derived *>'}}
-}
diff --git a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.conv/base.pass.cpp b/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.conv/base.pass.cpp
deleted file mode 100644
index 7fd85c92b327..000000000000
--- a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.conv/base.pass.cpp
+++ /dev/null
@@ -1,37 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-// <iterator>
-
-// __unconstrained_reverse_iterator
-
-// iterator_type base() const; // constexpr since C++17
-
-#include <iterator>
-#include <cassert>
-
-#include "test_macros.h"
-#include "test_iterators.h"
-
-TEST_CONSTEXPR_CXX17 bool test() {
-    typedef bidirectional_iterator<int*> Iter;
-    int i = 0;
-    Iter iter(&i);
-    std::__unconstrained_reverse_iterator<Iter> const reverse(iter);
-    std::__unconstrained_reverse_iterator<Iter>::iterator_type base = reverse.base();
-    assert(base == Iter(&i));
-    return true;
-}
-
-int main(int, char**) {
-    test();
-#if TEST_STD_VER > 14
-    static_assert(test(), "");
-#endif
-    return 0;
-}
diff --git a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.elem/arrow.pass.cpp b/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.elem/arrow.pass.cpp
deleted file mode 100644
index f0a181bcba88..000000000000
--- a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.elem/arrow.pass.cpp
+++ /dev/null
@@ -1,122 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-// <iterator>
-
-// __unconstrained_reverse_iterator
-
-// pointer operator->() const; // constexpr in C++17
-
-// Be sure to respect LWG 198:
-//    http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#198
-// LWG 198 was superseded by LWG 2360
-//    http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#2360
-
-
-#include <iterator>
-#include <list>
-#include <cassert>
-
-#include "test_macros.h"
-
-class A
-{
-    int data_;
-public:
-    A() : data_(1) {}
-    A(const A&) = default;
-    A& operator=(const A&) = default;
-    ~A() {data_ = -1;}
-
-    int get() const {return data_;}
-
-    friend bool operator==(const A& x, const A& y)
-        {return x.data_ == y.data_;}
-};
-
-template <class It>
-void
-test(It i, typename std::iterator_traits<It>::value_type x)
-{
-    std::__unconstrained_reverse_iterator<It> r(i);
-    assert(r->get() == x.get());
-}
-
-class B
-{
-    int data_;
-public:
-    B(int d=1) : data_(d) {}
-    B(const B&) = default;
-    B& operator=(const B&) = default;
-    ~B() {data_ = -1;}
-
-    int get() const {return data_;}
-
-    friend bool operator==(const B& x, const B& y)
-        {return x.data_ == y.data_;}
-    const B *operator&() const { return nullptr; }
-    B       *operator&()       { return nullptr; }
-};
-
-class C
-{
-    int data_;
-public:
-    TEST_CONSTEXPR C() : data_(1) {}
-
-    TEST_CONSTEXPR int get() const {return data_;}
-
-    friend TEST_CONSTEXPR bool operator==(const C& x, const C& y)
-        {return x.data_ == y.data_;}
-};
-
-TEST_CONSTEXPR  C gC;
-
-int main(int, char**)
-{
-  A a;
-  test(&a+1, A());
-
-  {
-    std::list<B> l;
-    l.push_back(B(0));
-    l.push_back(B(1));
-    l.push_back(B(2));
-
-    {
-      std::list<B>::const_iterator i = l.begin();
-      assert ( i->get() == 0 );  ++i;
-      assert ( i->get() == 1 );  ++i;
-      assert ( i->get() == 2 );  ++i;
-      assert ( i == l.end ());
-    }
-
-    {
-      std::list<B>::const_reverse_iterator ri = l.rbegin();
-      assert ( ri->get() == 2 );  ++ri;
-      assert ( ri->get() == 1 );  ++ri;
-      assert ( ri->get() == 0 );  ++ri;
-      assert ( ri == l.rend ());
-    }
-  }
-
-#if TEST_STD_VER > 14
-  {
-    typedef std::__unconstrained_reverse_iterator<const C *> RI;
-    constexpr RI it1 = RI(&gC+1);
-
-    static_assert(it1->get() == gC.get(), "");
-  }
-#endif
-  {
-    ((void)gC);
-  }
-
-  return 0;
-}
diff --git a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.elem/bracket.pass.cpp b/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.elem/bracket.pass.cpp
deleted file mode 100644
index f9beada9e4e6..000000000000
--- a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.elem/bracket.pass.cpp
+++ /dev/null
@@ -1,47 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-// <iterator>
-
-// __unconstrained_reverse_iterator
-
-// requires RandomAccessIterator<Iter>
-// unspecified operator[](difference_type n) const; // constexpr since C++17
-
-#include <iterator>
-#include <cassert>
-
-#include "test_macros.h"
-#include "test_iterators.h"
-
-template <class It>
-TEST_CONSTEXPR_CXX17 void test(It i,
-                               typename std::iterator_traits<It>::difference_type n,
-                               typename std::iterator_traits<It>::value_type x) {
-    typedef typename std::iterator_traits<It>::value_type value_type;
-    const std::__unconstrained_reverse_iterator<It> r(i);
-    value_type rr = r[n];
-    assert(rr == x);
-}
-
-TEST_CONSTEXPR_CXX17 bool tests() {
-    const char* s = "1234567890";
-    test(random_access_iterator<const char*>(s+5), 4, '1');
-    test(random_access_iterator<const char*>(s+5), 0, '5');
-    test(s+5, 4, '1');
-    test(s+5, 0, '5');
-    return true;
-}
-
-int main(int, char**) {
-    tests();
-#if TEST_STD_VER > 14
-    static_assert(tests(), "");
-#endif
-    return 0;
-}
diff --git a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.elem/dereference.pass.cpp b/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.elem/dereference.pass.cpp
deleted file mode 100644
index bd6b6e0df038..000000000000
--- a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.elem/dereference.pass.cpp
+++ /dev/null
@@ -1,63 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-// <iterator>
-
-// __unconstrained_reverse_iterator
-
-// reference operator*() const; // constexpr in C++17
-
-// Be sure to respect LWG 198:
-//    http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#198
-// LWG 198 was superseded by LWG 2360
-//    http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#2360
-
-#include <iterator>
-#include <cassert>
-
-#include "test_macros.h"
-
-class A
-{
-    int data_;
-public:
-    A() : data_(1) {}
-    A(const A&) = default;
-    A& operator=(const A&) = default;
-    ~A() {data_ = -1;}
-
-    friend bool operator==(const A& x, const A& y)
-        {return x.data_ == y.data_;}
-};
-
-template <class It>
-void
-test(It i, typename std::iterator_traits<It>::value_type x)
-{
-    std::__unconstrained_reverse_iterator<It> r(i);
-    assert(*r == x);
-}
-
-int main(int, char**)
-{
-    A a;
-    test(&a+1, A());
-
-#if TEST_STD_VER > 14
-    {
-        constexpr const char *p = "123456789";
-        typedef std::__unconstrained_reverse_iterator<const char *> RI;
-        constexpr RI it1 = RI(p+1);
-        constexpr RI it2 = RI(p+2);
-        static_assert(*it1 == p[0], "");
-        static_assert(*it2 == p[1], "");
-    }
-#endif
-
-  return 0;
-}
diff --git a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.nav/decrement-assign.pass.cpp b/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.nav/decrement-assign.pass.cpp
deleted file mode 100644
index 48be8a7399e4..000000000000
--- a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.nav/decrement-assign.pass.cpp
+++ /dev/null
@@ -1,43 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-// <iterator>
-
-// __unconstrained_reverse_iterator
-
-// requires RandomAccessIterator<Iter>
-// __unconstrained_reverse_iterator& operator-=(difference_type n); // constexpr in C++17
-
-#include <iterator>
-#include <cassert>
-
-#include "test_macros.h"
-#include "test_iterators.h"
-
-template <class It>
-TEST_CONSTEXPR_CXX17 void test(It i, typename std::iterator_traits<It>::difference_type n, It x) {
-    std::__unconstrained_reverse_iterator<It> r(i);
-    std::__unconstrained_reverse_iterator<It>& rr = r -= n;
-    assert(r.base() == x);
-    assert(&rr == &r);
-}
-
-TEST_CONSTEXPR_CXX17 bool tests() {
-    const char* s = "1234567890";
-    test(random_access_iterator<const char*>(s+5), 5, random_access_iterator<const char*>(s+10));
-    test(s+5, 5, s+10);
-    return true;
-}
-
-int main(int, char**) {
-    tests();
-#if TEST_STD_VER > 14
-    static_assert(tests(), "");
-#endif
-    return 0;
-}
diff --git a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.nav/increment-assign.pass.cpp b/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.nav/increment-assign.pass.cpp
deleted file mode 100644
index 115d95e1485c..000000000000
--- a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.nav/increment-assign.pass.cpp
+++ /dev/null
@@ -1,43 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-// <iterator>
-
-// __unconstrained_reverse_iterator
-
-// requires RandomAccessIterator<Iter>
-// __unconstrained_reverse_iterator& operator+=(difference_type n); // constexpr in C++17
-
-#include <iterator>
-#include <cassert>
-
-#include "test_macros.h"
-#include "test_iterators.h"
-
-template <class It>
-TEST_CONSTEXPR_CXX17 void test(It i, typename std::iterator_traits<It>::difference_type n, It x) {
-    std::__unconstrained_reverse_iterator<It> r(i);
-    std::__unconstrained_reverse_iterator<It>& rr = r += n;
-    assert(r.base() == x);
-    assert(&rr == &r);
-}
-
-TEST_CONSTEXPR_CXX17 bool tests() {
-    char const* s = "1234567890";
-    test(random_access_iterator<const char*>(s+5), 5, random_access_iterator<const char*>(s));
-    test(s+5, 5, s);
-    return true;
-}
-
-int main(int, char**) {
-    tests();
-#if TEST_STD_VER > 14
-    static_assert(tests(), "");
-#endif
-    return 0;
-}
diff --git a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.nav/minus.pass.cpp b/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.nav/minus.pass.cpp
deleted file mode 100644
index c3a4d1fd9e36..000000000000
--- a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.nav/minus.pass.cpp
+++ /dev/null
@@ -1,42 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-// <iterator>
-
-// __unconstrained_reverse_iterator
-
-// requires RandomAccessIterator<Iter>
-// __unconstrained_reverse_iterator operator-(difference_type n) const; // constexpr in C++17
-
-#include <iterator>
-#include <cassert>
-
-#include "test_macros.h"
-#include "test_iterators.h"
-
-template <class It>
-TEST_CONSTEXPR_CXX17 void test(It i, typename std::iterator_traits<It>::difference_type n, It x) {
-    const std::__unconstrained_reverse_iterator<It> r(i);
-    std::__unconstrained_reverse_iterator<It> rr = r - n;
-    assert(rr.base() == x);
-}
-
-TEST_CONSTEXPR_CXX17 bool tests() {
-    const char* s = "1234567890";
-    test(random_access_iterator<const char*>(s+5), 5, random_access_iterator<const char*>(s+10));
-    test(s+5, 5, s+10);
-    return true;
-}
-
-int main(int, char**) {
-    tests();
-#if TEST_STD_VER > 14
-    static_assert(tests(), "");
-#endif
-    return 0;
-}
diff --git a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.nav/plus.pass.cpp b/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.nav/plus.pass.cpp
deleted file mode 100644
index 164c5abe8a35..000000000000
--- a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.nav/plus.pass.cpp
+++ /dev/null
@@ -1,42 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-// <iterator>
-
-// __unconstrained_reverse_iterator
-
-// requires RandomAccessIterator<Iter>
-// __unconstrained_reverse_iterator operator+(difference_type n) const; // constexpr in C++17
-
-#include <iterator>
-#include <cassert>
-
-#include "test_macros.h"
-#include "test_iterators.h"
-
-template <class It>
-TEST_CONSTEXPR_CXX17 void test(It i, typename std::iterator_traits<It>::difference_type n, It x) {
-    const std::__unconstrained_reverse_iterator<It> r(i);
-    std::__unconstrained_reverse_iterator<It> rr = r + n;
-    assert(rr.base() == x);
-}
-
-TEST_CONSTEXPR_CXX17 bool tests() {
-    const char* s = "1234567890";
-    test(random_access_iterator<const char*>(s+5), 5, random_access_iterator<const char*>(s));
-    test(s+5, 5, s);
-    return true;
-}
-
-int main(int, char**) {
-    tests();
-#if TEST_STD_VER > 14
-    static_assert(tests(), "");
-#endif
-    return 0;
-}
diff --git a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.nav/postdecrement.pass.cpp b/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.nav/postdecrement.pass.cpp
deleted file mode 100644
index 3220c1f9b1eb..000000000000
--- a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.nav/postdecrement.pass.cpp
+++ /dev/null
@@ -1,43 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-// <iterator>
-
-// __unconstrained_reverse_iterator
-
-// __unconstrained_reverse_iterator operator--(int); // constexpr in C++17
-
-#include <iterator>
-#include <cassert>
-
-#include "test_macros.h"
-#include "test_iterators.h"
-
-template <class It>
-TEST_CONSTEXPR_CXX17 void test(It i, It x) {
-    std::__unconstrained_reverse_iterator<It> r(i);
-    std::__unconstrained_reverse_iterator<It> rr = r--;
-    assert(r.base() == x);
-    assert(rr.base() == i);
-}
-
-TEST_CONSTEXPR_CXX17 bool tests() {
-    const char* s = "123";
-    test(bidirectional_iterator<const char*>(s+1), bidirectional_iterator<const char*>(s+2));
-    test(random_access_iterator<const char*>(s+1), random_access_iterator<const char*>(s+2));
-    test(s+1, s+2);
-    return true;
-}
-
-int main(int, char**) {
-    tests();
-#if TEST_STD_VER > 14
-    static_assert(tests(), "");
-#endif
-    return 0;
-}
diff --git a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.nav/postincrement.pass.cpp b/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.nav/postincrement.pass.cpp
deleted file mode 100644
index 47477fe89545..000000000000
--- a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.nav/postincrement.pass.cpp
+++ /dev/null
@@ -1,43 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-// <iterator>
-
-// __unconstrained_reverse_iterator
-
-// __unconstrained_reverse_iterator operator++(int); // constexpr in C++17
-
-#include <iterator>
-#include <cassert>
-
-#include "test_macros.h"
-#include "test_iterators.h"
-
-template <class It>
-TEST_CONSTEXPR_CXX17 void test(It i, It x) {
-    std::__unconstrained_reverse_iterator<It> r(i);
-    std::__unconstrained_reverse_iterator<It> rr = r++;
-    assert(r.base() == x);
-    assert(rr.base() == i);
-}
-
-TEST_CONSTEXPR_CXX17 bool tests() {
-    const char* s = "123";
-    test(bidirectional_iterator<const char*>(s+1), bidirectional_iterator<const char*>(s));
-    test(random_access_iterator<const char*>(s+1), random_access_iterator<const char*>(s));
-    test(s+1, s);
-    return true;
-}
-
-int main(int, char**) {
-    tests();
-#if TEST_STD_VER > 14
-    static_assert(tests(), "");
-#endif
-    return 0;
-}
diff --git a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.nav/predecrement.pass.cpp b/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.nav/predecrement.pass.cpp
deleted file mode 100644
index 6ad41aeaf17a..000000000000
--- a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.nav/predecrement.pass.cpp
+++ /dev/null
@@ -1,43 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-// <iterator>
-
-// __unconstrained_reverse_iterator
-
-// __unconstrained_reverse_iterator& operator--(); // constexpr in C++17
-
-#include <iterator>
-#include <cassert>
-
-#include "test_macros.h"
-#include "test_iterators.h"
-
-template <class It>
-TEST_CONSTEXPR_CXX17 void test(It i, It x) {
-    std::__unconstrained_reverse_iterator<It> r(i);
-    std::__unconstrained_reverse_iterator<It>& rr = --r;
-    assert(r.base() == x);
-    assert(&rr == &r);
-}
-
-TEST_CONSTEXPR_CXX17 bool tests() {
-    const char* s = "123";
-    test(bidirectional_iterator<const char*>(s+1), bidirectional_iterator<const char*>(s+2));
-    test(random_access_iterator<const char*>(s+1), random_access_iterator<const char*>(s+2));
-    test(s+1, s+2);
-    return true;
-}
-
-int main(int, char**) {
-    tests();
-#if TEST_STD_VER > 14
-    static_assert(tests(), "");
-#endif
-    return 0;
-}
diff --git a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.nav/preincrement.pass.cpp b/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.nav/preincrement.pass.cpp
deleted file mode 100644
index 9c7e5b41738e..000000000000
--- a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.nav/preincrement.pass.cpp
+++ /dev/null
@@ -1,43 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-// <iterator>
-
-// __unconstrained_reverse_iterator
-
-// __unconstrained_reverse_iterator& operator++(); // constexpr in C++17
-
-#include <iterator>
-#include <cassert>
-
-#include "test_macros.h"
-#include "test_iterators.h"
-
-template <class It>
-TEST_CONSTEXPR_CXX17 void test(It i, It x) {
-    std::__unconstrained_reverse_iterator<It> r(i);
-    std::__unconstrained_reverse_iterator<It>& rr = ++r;
-    assert(r.base() == x);
-    assert(&rr == &r);
-}
-
-TEST_CONSTEXPR_CXX17 bool tests() {
-    const char* s = "123";
-    test(bidirectional_iterator<const char*>(s+1), bidirectional_iterator<const char*>(s));
-    test(random_access_iterator<const char*>(s+1), random_access_iterator<const char*>(s));
-    test(s+1, s);
-    return true;
-}
-
-int main(int, char**) {
-    tests();
-#if TEST_STD_VER > 14
-    static_assert(tests(), "");
-#endif
-    return 0;
-}
diff --git a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.nonmember/minus.pass.cpp b/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.nonmember/minus.pass.cpp
deleted file mode 100644
index 632e2655dea0..000000000000
--- a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/reverse.iter.nonmember/minus.pass.cpp
+++ /dev/null
@@ -1,59 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-// <iterator>
-
-// __unconstrained_reverse_iterator
-
-// template <RandomAccessIterator Iter1, RandomAccessIterator Iter2>
-//   requires HasMinus<Iter2, Iter1>
-// auto operator-(const __unconstrained_reverse_iterator<Iter1>& x, const __unconstrained_reverse_iterator<Iter2>& y) // constexpr in C++17
-//  -> decltype(y.base() - x.base());
-
-#include <iterator>
-#include <cstddef>
-#include <cassert>
-#include <type_traits>
-
-#include "test_macros.h"
-#include "test_iterators.h"
-
-template <class, class, class = void> struct HasMinus : std::false_type {};
-template <class R1, class R2> struct HasMinus<R1, R2, decltype((R1() - R2(), void()))> : std::true_type {};
-
-template <class It1, class It2>
-TEST_CONSTEXPR_CXX17 void test(It1 l, It2 r, std::ptrdiff_t x) {
-    const std::__unconstrained_reverse_iterator<It1> r1(l);
-    const std::__unconstrained_reverse_iterator<It2> r2(r);
-    assert((r1 - r2) == x);
-}
-
-TEST_CONSTEXPR_CXX17 bool tests() {
-    char s[3] = {0};
-
-    // Test same base iterator type
-    test(s, s, 0);
-    test(s, s+1, 1);
-    test(s+1, s, -1);
-
-    // Test non-subtractable base iterator types
-    static_assert( HasMinus<std::__unconstrained_reverse_iterator<int*>, std::__unconstrained_reverse_iterator<int*> >::value, "");
-#if TEST_STD_VER >= 11
-    static_assert(!HasMinus<std::__unconstrained_reverse_iterator<int*>, std::__unconstrained_reverse_iterator<char*> >::value, "");
-#endif
-
-    return true;
-}
-
-int main(int, char**) {
-    tests();
-#if TEST_STD_VER > 14
-    static_assert(tests(), "");
-#endif
-    return 0;
-}
diff --git a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/types.compile.pass.cpp b/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/types.compile.pass.cpp
deleted file mode 100644
index f8ffef364f37..000000000000
--- a/libcxx/test/libcxx/iterators/predef.iterators/__unconstrained_reverse_iterator/types.compile.pass.cpp
+++ /dev/null
@@ -1,106 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-// <iterator>
-
-// __unconstrained_reverse_iterator
-
-// Test nested types and data member:
-
-// template <BidirectionalIterator Iter>
-// class __unconstrained_reverse_iterator {
-// protected:
-//   Iter current;
-// public:
-//   iterator<typename iterator_traits<Iterator>::iterator_category,
-//   typename iterator_traits<Iterator>::value_type,
-//   typename iterator_traits<Iterator>::difference_type,
-//   typename iterator_traits<Iterator>::pointer,
-//   typename iterator_traits<Iterator>::reference> {
-// };
-
-#include <iterator>
-#include <type_traits>
-
-#include "test_macros.h"
-#include "test_iterators.h"
-
-template <class It>
-void test() {
-  typedef std::__unconstrained_reverse_iterator<It> R;
-  typedef std::iterator_traits<It> T;
-  static_assert((std::is_same<typename R::iterator_type, It>::value), "");
-  static_assert((std::is_same<typename R::value_type, typename T::value_type>::value), "");
-  static_assert((std::is_same<typename R::difference_type, typename T::difference_type>::value), "");
-  static_assert((std::is_same<typename R::reference, typename T::reference>::value), "");
-  static_assert((std::is_same<typename R::pointer, typename std::iterator_traits<It>::pointer>::value), "");
-
-#if TEST_STD_VER <= 14
-  typedef std::iterator<typename T::iterator_category, typename T::value_type> iterator_base;
-  static_assert((std::is_base_of<iterator_base, R>::value), "");
-#endif
-#if TEST_STD_VER > 17
-  if constexpr (std::is_same_v<typename T::iterator_category, std::contiguous_iterator_tag>) {
-    static_assert((std::is_same<typename R::iterator_category, std::random_access_iterator_tag>::value), "");
-  } else {
-    static_assert((std::is_same<typename R::iterator_category, typename T::iterator_category>::value), "");
-  }
-#else
-  static_assert((std::is_same<typename R::iterator_category, typename T::iterator_category>::value), "");
-#endif
-}
-
-#if TEST_STD_VER > 17
-
-struct FooIter {
-  using iterator_category = std::bidirectional_iterator_tag;
-  using value_type = void*;
-  using difference_type = void*;
-  using pointer = void*;
-  using reference = int&;
-  int& operator*() const;
-};
-template <>
-struct std::indirectly_readable_traits<FooIter> {
-  using value_type = int;
-};
-template <>
-struct std::incrementable_traits<FooIter> {
-  using difference_type = char;
-};
-
-// Not using `FooIter::value_type`.
-static_assert(std::is_same_v<typename std::__unconstrained_reverse_iterator<FooIter>::value_type, int>);
-// Not using `FooIter::difference_type`.
-static_assert(std::is_same_v<typename std::__unconstrained_reverse_iterator<FooIter>::difference_type, char>);
-
-#endif
-
-struct BarIter {
-  bool& operator*() const;
-};
-template <>
-struct std::iterator_traits<BarIter> {
-  using difference_type = char;
-  using value_type = char;
-  using pointer = char*;
-  using reference = char&;
-  using iterator_category = std::bidirectional_iterator_tag;
-};
-
-#if TEST_STD_VER > 17
-  static_assert(std::is_same_v<typename std::__unconstrained_reverse_iterator<BarIter>::reference, bool&>);
-#else
-  static_assert(std::is_same<typename std::__unconstrained_reverse_iterator<BarIter>::reference, char&>::value, "");
-#endif
-
-void test_all() {
-  test<bidirectional_iterator<char*> >();
-  test<random_access_iterator<char*> >();
-  test<char*>();
-}