diff --git a/libcxx/include/__algorithm/ranges_unique.h b/libcxx/include/__algorithm/ranges_unique.h
index a817359abd889..64191e3c94674 100644
--- a/libcxx/include/__algorithm/ranges_unique.h
+++ b/libcxx/include/__algorithm/ranges_unique.h
@@ -47,8 +47,8 @@ struct __unique {
             indirect_equivalence_relation<projected<_Iter, _Proj>> _Comp = ranges::equal_to>
   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr subrange<_Iter>
   operator()(_Iter __first, _Sent __last, _Comp __comp = {}, _Proj __proj = {}) const {
-    auto __ret =
-        std::__unique<_RangeAlgPolicy>(std::move(__first), std::move(__last), std::__make_projected(__comp, __proj));
+    auto __ret = std::__unique_sorted_range<_RangeAlgPolicy>(
+        std::move(__first), std::move(__last), std::__make_projected(__comp, __proj));
     return {std::move(__ret.first), std::move(__ret.second)};
   }
 
@@ -58,7 +58,7 @@ struct __unique {
     requires permutable<iterator_t<_Range>>
   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr borrowed_subrange_t<_Range>
   operator()(_Range&& __range, _Comp __comp = {}, _Proj __proj = {}) const {
-    auto __ret = std::__unique<_RangeAlgPolicy>(
+    auto __ret = std::__unique_sorted_range<_RangeAlgPolicy>(
         ranges::begin(__range), ranges::end(__range), std::__make_projected(__comp, __proj));
     return {std::move(__ret.first), std::move(__ret.second)};
   }
diff --git a/libcxx/include/__algorithm/unique.h b/libcxx/include/__algorithm/unique.h
index 307c424a7c2fb..4aa14fbc92e96 100644
--- a/libcxx/include/__algorithm/unique.h
+++ b/libcxx/include/__algorithm/unique.h
@@ -29,9 +29,10 @@ _LIBCPP_BEGIN_NAMESPACE_STD
 
 // unique
 
+// For this unchecked algorithm, __pred does not need to be an equivalence relation.
 template <class _AlgPolicy, class _Iter, class _Sent, class _BinaryPredicate>
 [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 std::pair<_Iter, _Iter>
-__unique(_Iter __first, _Sent __last, _BinaryPredicate&& __pred) {
+__unique_sorted_range(_Iter __first, _Sent __last, _BinaryPredicate&& __pred) {
   __identity __proj;
   __first = std::__adjacent_find(__first, __last, __pred, __proj);
   if (__first != __last) {
@@ -50,7 +51,7 @@ __unique(_Iter __first, _Sent __last, _BinaryPredicate&& __pred) {
 template <class _ForwardIterator, class _BinaryPredicate>
 [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _ForwardIterator
 unique(_ForwardIterator __first, _ForwardIterator __last, _BinaryPredicate __pred) {
-  return std::__unique<_ClassicAlgPolicy>(std::move(__first), std::move(__last), __pred).first;
+  return std::__unique_sorted_range<_ClassicAlgPolicy>(std::move(__first), std::move(__last), __pred).first;
 }
 
 template <class _ForwardIterator>
diff --git a/libcxx/include/__flat_map/flat_map.h b/libcxx/include/__flat_map/flat_map.h
index 50487cada24c0..d0d83fecf3fe4 100644
--- a/libcxx/include/__flat_map/flat_map.h
+++ b/libcxx/include/__flat_map/flat_map.h
@@ -10,6 +10,7 @@
 #ifndef _LIBCPP___FLAT_MAP_FLAT_MAP_H
 #define _LIBCPP___FLAT_MAP_FLAT_MAP_H
 
+#include <__algorithm/iterator_operations.h>
 #include <__algorithm/lexicographical_compare_three_way.h>
 #include <__algorithm/lower_bound.h>
 #include <__algorithm/min.h>
@@ -17,8 +18,8 @@
 #include <__algorithm/ranges_equal.h>
 #include <__algorithm/ranges_inplace_merge.h>
 #include <__algorithm/ranges_sort.h>
-#include <__algorithm/ranges_unique.h>
 #include <__algorithm/remove_if.h>
+#include <__algorithm/unique.h>
 #include <__algorithm/upper_bound.h>
 #include <__assert>
 #include <__compare/synth_three_way.h>
@@ -944,7 +945,8 @@ class flat_map {
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 void __sort_and_unique() {
     auto __zv = ranges::views::zip(__containers_.keys, __containers_.values);
     ranges::sort(__zv, __compare_, [](const auto& __p) -> decltype(auto) { return std::get<0>(__p); });
-    auto __dup_start = ranges::unique(__zv, __key_equiv(__compare_)).begin();
+    auto __dup_start =
+        std::__unique_sorted_range<_RangeAlgPolicy>(__zv.begin(), __zv.end(), __key_not_less(__compare_)).first;
     auto __dist      = ranges::distance(__zv.begin(), __dup_start);
     __containers_.keys.erase(__containers_.keys.begin() + __dist, __containers_.keys.end());
     __containers_.values.erase(__containers_.values.begin() + __dist, __containers_.values.end());
@@ -979,7 +981,8 @@ class flat_map {
       }
       ranges::inplace_merge(__zv.begin(), __zv.begin() + __append_start_offset, __end, __compare_key);
 
-      auto __dup_start = ranges::unique(__zv, __key_equiv(__compare_)).begin();
+      auto __dup_start =
+          std::__unique_sorted_range<_RangeAlgPolicy>(__zv.begin(), __zv.end(), __key_not_less(__compare_)).first;
       auto __dist      = ranges::distance(__zv.begin(), __dup_start);
       __containers_.keys.erase(__containers_.keys.begin() + __dist, __containers_.keys.end());
       __containers_.values.erase(__containers_.values.begin() + __dist, __containers_.values.end());
@@ -1135,11 +1138,11 @@ class flat_map {
   containers __containers_;
   _LIBCPP_NO_UNIQUE_ADDRESS key_compare __compare_;
 
-  struct __key_equiv {
-    _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 __key_equiv(key_compare __c) : __comp_(__c) {}
-    _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 bool
-    operator()(const_reference __x, const_reference __y) const {
-      return !__comp_(std::get<0>(__x), std::get<0>(__y)) && !__comp_(std::get<0>(__y), std::get<0>(__x));
+  struct __key_not_less {
+    _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 __key_not_less(key_compare __c) : __comp_(__c) {}
+    _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 bool operator()(const auto& __x, const auto& __y) const {
+      // __x is less or equal to __y because the range is already sorted
+      return !__comp_(std::get<0>(__x), std::get<0>(__y));
     }
     key_compare __comp_;
   };
diff --git a/libcxx/include/__flat_set/flat_set.h b/libcxx/include/__flat_set/flat_set.h
index 57c3926e33b68..d97b66e1cdf5d 100644
--- a/libcxx/include/__flat_set/flat_set.h
+++ b/libcxx/include/__flat_set/flat_set.h
@@ -10,14 +10,15 @@
 #ifndef _LIBCPP___FLAT_SET_FLAT_SET_H
 #define _LIBCPP___FLAT_SET_FLAT_SET_H
 
+#include <__algorithm/iterator_operations.h>
 #include <__algorithm/lexicographical_compare_three_way.h>
 #include <__algorithm/lower_bound.h>
 #include <__algorithm/ranges_adjacent_find.h>
 #include <__algorithm/ranges_equal.h>
 #include <__algorithm/ranges_inplace_merge.h>
 #include <__algorithm/ranges_sort.h>
-#include <__algorithm/ranges_unique.h>
 #include <__algorithm/remove_if.h>
+#include <__algorithm/unique.h>
 #include <__algorithm/upper_bound.h>
 #include <__assert>
 #include <__compare/synth_three_way.h>
@@ -688,7 +689,8 @@ class flat_set {
   // is no invariant state to preserve
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 void __sort_and_unique() {
     ranges::sort(__keys_, __compare_);
-    auto __dup_start = ranges::unique(__keys_, __key_equiv(__compare_)).begin();
+    auto __dup_start =
+        std::__unique_sorted_range<_RangeAlgPolicy>(__keys_.begin(), __keys_.end(), __key_not_less(__compare_)).first;
     __keys_.erase(__dup_start, __keys_.end());
   }
 
@@ -706,7 +708,8 @@ class flat_set {
       }
       ranges::inplace_merge(__keys_.begin(), __keys_.begin() + __old_size, __keys_.end(), __compare_);
 
-      auto __dup_start = ranges::unique(__keys_, __key_equiv(__compare_)).begin();
+      auto __dup_start =
+          std::__unique_sorted_range<_RangeAlgPolicy>(__keys_.begin(), __keys_.end(), __key_not_less(__compare_)).first;
       __keys_.erase(__dup_start, __keys_.end());
     }
     __on_failure.__complete();
@@ -781,11 +784,11 @@ class flat_set {
   _KeyContainer __keys_;
   _LIBCPP_NO_UNIQUE_ADDRESS key_compare __compare_;
 
-  struct __key_equiv {
-    _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 __key_equiv(key_compare __c) : __comp_(__c) {}
-    _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 bool
-    operator()(const_reference __x, const_reference __y) const {
-      return !__comp_(__x, __y) && !__comp_(__y, __x);
+  struct __key_not_less {
+    _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 __key_not_less(key_compare __c) : __comp_(__c) {}
+    _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 bool operator()(const auto& __x, const auto& __y) const {
+      // __x is less or equal to __y because the range is already sorted
+      return !__comp_(__x, __y);
     }
     key_compare __comp_;
   };