diff --git a/libcxx/include/CMakeLists.txt b/libcxx/include/CMakeLists.txt
--- a/libcxx/include/CMakeLists.txt
+++ b/libcxx/include/CMakeLists.txt
@@ -382,7 +382,6 @@
   __functional/reference_wrapper.h
   __functional/unary_function.h
   __functional/unary_negate.h
-  __functional/unwrap_ref.h
   __functional/weak_result_type.h
   __fwd/array.h
   __fwd/fstream.h
@@ -748,6 +747,7 @@
   __type_traits/type_identity.h
   __type_traits/type_list.h
   __type_traits/underlying_type.h
+  __type_traits/unwrap_ref.h
   __type_traits/void_t.h
   __undef_macros
   __utility/as_const.h
diff --git a/libcxx/include/__functional/unwrap_ref.h b/libcxx/include/__type_traits/unwrap_ref.h
rename from libcxx/include/__functional/unwrap_ref.h
rename to libcxx/include/__type_traits/unwrap_ref.h
--- a/libcxx/include/__functional/unwrap_ref.h
+++ b/libcxx/include/__type_traits/unwrap_ref.h
@@ -6,8 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef _LIBCPP___FUNCTIONAL_UNWRAP_REF_H
-#define _LIBCPP___FUNCTIONAL_UNWRAP_REF_H
+#ifndef _LIBCPP___TYPE_TRAITS_UNWRAP_REF_H
+#define _LIBCPP___TYPE_TRAITS_UNWRAP_REF_H
 
 #include <__config>
 #include <__type_traits/decay.h>
@@ -42,7 +42,7 @@
 
 template <class _Tp>
 using unwrap_ref_decay_t = typename unwrap_ref_decay<_Tp>::type;
-#endif // > C++17
+#endif // _LIBCPP_STD_VER >= 20
 
 template <class _Tp>
 struct __unwrap_ref_decay
@@ -55,4 +55,4 @@
 
 _LIBCPP_END_NAMESPACE_STD
 
-#endif // _LIBCPP___FUNCTIONAL_UNWRAP_REF_H
+#endif // _LIBCPP___TYPE_TRAITS_UNWRAP_REF_H
diff --git a/libcxx/include/__utility/pair.h b/libcxx/include/__utility/pair.h
--- a/libcxx/include/__utility/pair.h
+++ b/libcxx/include/__utility/pair.h
@@ -12,7 +12,6 @@
 #include <__compare/common_comparison_category.h>
 #include <__compare/synth_three_way.h>
 #include <__config>
-#include <__functional/unwrap_ref.h>
 #include <__fwd/get.h>
 #include <__fwd/tuple.h>
 #include <__tuple/sfinae_helpers.h>
@@ -39,6 +38,7 @@
 #include <__type_traits/is_same.h>
 #include <__type_traits/is_swappable.h>
 #include <__type_traits/nat.h>
+#include <__type_traits/unwrap_ref.h>
 #include <__utility/forward.h>
 #include <__utility/move.h>
 #include <__utility/piecewise_construct.h>
diff --git a/libcxx/include/functional b/libcxx/include/functional
--- a/libcxx/include/functional
+++ b/libcxx/include/functional
@@ -541,7 +541,7 @@
 #include <__functional/reference_wrapper.h>
 #include <__functional/unary_function.h>
 #include <__functional/unary_negate.h>
-#include <__functional/unwrap_ref.h>
+#include <__type_traits/unwrap_ref.h>
 #include <__utility/forward.h>
 #include <memory> // TODO: find out why removing this breaks the modules build
 #include <typeinfo>
diff --git a/libcxx/include/module.modulemap.in b/libcxx/include/module.modulemap.in
--- a/libcxx/include/module.modulemap.in
+++ b/libcxx/include/module.modulemap.in
@@ -948,6 +948,8 @@
   }
   module functional {
     header "functional"
+    // the contents of __type_traits/unwrap_ref.h should be available from functional too.
+    export type_traits.unwrap_ref
     export *
 
     module __functional {
@@ -981,7 +983,6 @@
       module reference_wrapper          { private header "__functional/reference_wrapper.h" }
       module unary_function             { private header "__functional/unary_function.h" }
       module unary_negate               { private header "__functional/unary_negate.h" }
-      module unwrap_ref                 { private header "__functional/unwrap_ref.h" }
       module weak_result_type           { private header "__functional/weak_result_type.h" }
     }
   }
@@ -1490,7 +1491,6 @@
   }
   module type_traits {
     header "type_traits"
-    export functional.__functional.unwrap_ref
     export *
 
     module add_const                           { private header "__type_traits/add_const.h" }
@@ -1646,6 +1646,7 @@
 
       export type_traits
     }
+    module unwrap_ref                          { private header "__type_traits/unwrap_ref.h" }
     module void_t                              { private header "__type_traits/void_t.h" }
   }
   module typeindex {
diff --git a/libcxx/include/tuple b/libcxx/include/tuple
--- a/libcxx/include/tuple
+++ b/libcxx/include/tuple
@@ -206,7 +206,6 @@
 #include <__compare/synth_three_way.h>
 #include <__config>
 #include <__functional/invoke.h>
-#include <__functional/unwrap_ref.h>
 #include <__fwd/array.h>
 #include <__memory/allocator_arg_t.h>
 #include <__memory/uses_allocator.h>
@@ -244,6 +243,7 @@
 #include <__type_traits/negation.h>
 #include <__type_traits/remove_cvref.h>
 #include <__type_traits/remove_reference.h>
+#include <__type_traits/unwrap_ref.h>
 #include <__utility/forward.h>
 #include <__utility/integer_sequence.h>
 #include <__utility/move.h>
diff --git a/libcxx/include/type_traits b/libcxx/include/type_traits
--- a/libcxx/include/type_traits
+++ b/libcxx/include/type_traits
@@ -532,6 +532,7 @@
 #include <__type_traits/result_of.h>
 #include <__type_traits/type_identity.h>
 #include <__type_traits/underlying_type.h>
+#include <__type_traits/unwrap_ref.h>
 #include <__type_traits/void_t.h>
 #include <__utility/declval.h>
 #include <cstddef>
diff --git a/libcxx/test/libcxx/private_headers.verify.cpp b/libcxx/test/libcxx/private_headers.verify.cpp
--- a/libcxx/test/libcxx/private_headers.verify.cpp
+++ b/libcxx/test/libcxx/private_headers.verify.cpp
@@ -424,7 +424,6 @@
 #include <__functional/reference_wrapper.h> // expected-error@*:* {{use of private header from outside its module: '__functional/reference_wrapper.h'}}
 #include <__functional/unary_function.h> // expected-error@*:* {{use of private header from outside its module: '__functional/unary_function.h'}}
 #include <__functional/unary_negate.h> // expected-error@*:* {{use of private header from outside its module: '__functional/unary_negate.h'}}
-#include <__functional/unwrap_ref.h> // expected-error@*:* {{use of private header from outside its module: '__functional/unwrap_ref.h'}}
 #include <__functional/weak_result_type.h> // expected-error@*:* {{use of private header from outside its module: '__functional/weak_result_type.h'}}
 #include <__fwd/array.h> // expected-error@*:* {{use of private header from outside its module: '__fwd/array.h'}}
 #include <__fwd/fstream.h> // expected-error@*:* {{use of private header from outside its module: '__fwd/fstream.h'}}
@@ -764,6 +763,7 @@
 #include <__type_traits/type_identity.h> // expected-error@*:* {{use of private header from outside its module: '__type_traits/type_identity.h'}}
 #include <__type_traits/type_list.h> // expected-error@*:* {{use of private header from outside its module: '__type_traits/type_list.h'}}
 #include <__type_traits/underlying_type.h> // expected-error@*:* {{use of private header from outside its module: '__type_traits/underlying_type.h'}}
+#include <__type_traits/unwrap_ref.h> // expected-error@*:* {{use of private header from outside its module: '__type_traits/unwrap_ref.h'}}
 #include <__type_traits/void_t.h> // expected-error@*:* {{use of private header from outside its module: '__type_traits/void_t.h'}}
 #include <__utility/as_const.h> // expected-error@*:* {{use of private header from outside its module: '__utility/as_const.h'}}
 #include <__utility/auto_cast.h> // expected-error@*:* {{use of private header from outside its module: '__utility/auto_cast.h'}}
diff --git a/libcxx/utils/data/ignore_format.txt b/libcxx/utils/data/ignore_format.txt
--- a/libcxx/utils/data/ignore_format.txt
+++ b/libcxx/utils/data/ignore_format.txt
@@ -395,7 +395,6 @@
 libcxx/include/__functional/reference_wrapper.h
 libcxx/include/__functional/unary_function.h
 libcxx/include/__functional/unary_negate.h
-libcxx/include/__functional/unwrap_ref.h
 libcxx/include/__functional/weak_result_type.h
 libcxx/include/future
 libcxx/include/__fwd/fstream.h
@@ -780,6 +779,7 @@
 libcxx/include/__type_traits/type_identity.h
 libcxx/include/__type_traits/type_list.h
 libcxx/include/__type_traits/underlying_type.h
+libcxx/include/__type_traits/unwrap_ref.h
 libcxx/include/__type_traits/void_t.h
 libcxx/include/uchar.h
 libcxx/include/unordered_map