diff --git a/libcxx/include/CMakeLists.txt b/libcxx/include/CMakeLists.txt
--- a/libcxx/include/CMakeLists.txt
+++ b/libcxx/include/CMakeLists.txt
@@ -264,9 +264,9 @@
   __tree
   __tuple
   __undef_macros
-  __utility/__decay_copy.h
   __utility/as_const.h
   __utility/cmp.h
+  __utility/decay_copy.h
   __utility/declval.h
   __utility/exchange.h
   __utility/forward.h
diff --git a/libcxx/include/__ranges/access.h b/libcxx/include/__ranges/access.h
--- a/libcxx/include/__ranges/access.h
+++ b/libcxx/include/__ranges/access.h
@@ -13,8 +13,8 @@
 #include <__iterator/concepts.h>
 #include <__iterator/readable_traits.h>
 #include <__ranges/enable_borrowed_range.h>
-#include <__utility/__decay_copy.h>
 #include <__utility/as_const.h>
+#include <__utility/decay_copy.h>
 #include <__utility/forward.h>
 #include <concepts>
 #include <type_traits>
diff --git a/libcxx/include/__ranges/all.h b/libcxx/include/__ranges/all.h
--- a/libcxx/include/__ranges/all.h
+++ b/libcxx/include/__ranges/all.h
@@ -17,7 +17,7 @@
 #include <__ranges/range_adaptor.h>
 #include <__ranges/ref_view.h>
 #include <__ranges/subrange.h>
-#include <__utility/__decay_copy.h>
+#include <__utility/decay_copy.h>
 #include <__utility/declval.h>
 #include <__utility/forward.h>
 #include <type_traits>
diff --git a/libcxx/include/__ranges/counted.h b/libcxx/include/__ranges/counted.h
--- a/libcxx/include/__ranges/counted.h
+++ b/libcxx/include/__ranges/counted.h
@@ -18,7 +18,7 @@
 #include <__memory/pointer_traits.h>
 #include <__ranges/concepts.h>
 #include <__ranges/subrange.h>
-#include <__utility/__decay_copy.h>
+#include <__utility/decay_copy.h>
 #include <__utility/declval.h>
 #include <__utility/forward.h>
 #include <__utility/move.h>
diff --git a/libcxx/include/__ranges/size.h b/libcxx/include/__ranges/size.h
--- a/libcxx/include/__ranges/size.h
+++ b/libcxx/include/__ranges/size.h
@@ -13,7 +13,7 @@
 #include <__iterator/concepts.h>
 #include <__iterator/iterator_traits.h>
 #include <__ranges/access.h>
-#include <__utility/__decay_copy.h>
+#include <__utility/decay_copy.h>
 #include <__utility/forward.h>
 #include <concepts>
 #include <type_traits>
diff --git a/libcxx/include/__utility/__decay_copy.h b/libcxx/include/__utility/decay_copy.h
rename from libcxx/include/__utility/__decay_copy.h
rename to libcxx/include/__utility/decay_copy.h
--- a/libcxx/include/__utility/__decay_copy.h
+++ b/libcxx/include/__utility/decay_copy.h
@@ -7,8 +7,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef _LIBCPP___TYPE_TRAITS_DECAY_COPY_H
-#define _LIBCPP___TYPE_TRAITS_DECAY_COPY_H
+#ifndef _LIBCPP___UTILITY_DECAY_COPY_H
+#define _LIBCPP___UTILITY_DECAY_COPY_H
 
 #include <__config>
 #include <__utility/forward.h>
@@ -36,4 +36,4 @@
 
 _LIBCPP_POP_MACROS
 
-#endif // _LIBCPP___TYPE_TRAITS_DECAY_COPY_H
+#endif // _LIBCPP___UTILITY_DECAY_COPY_H
diff --git a/libcxx/include/future b/libcxx/include/future
--- a/libcxx/include/future
+++ b/libcxx/include/future
@@ -366,7 +366,7 @@
 #include <__debug>
 #include <__memory/allocator_arg_t.h>
 #include <__memory/uses_allocator.h>
-#include <__utility/__decay_copy.h>
+#include <__utility/decay_copy.h>
 #include <__utility/forward.h>
 #include <chrono>
 #include <exception>
diff --git a/libcxx/include/module.modulemap b/libcxx/include/module.modulemap
--- a/libcxx/include/module.modulemap
+++ b/libcxx/include/module.modulemap
@@ -789,9 +789,9 @@
     export *
 
     module __utility {
-      module __decay_copy        { private header "__utility/__decay_copy.h"        }
       module as_const            { private header "__utility/as_const.h"            }
       module cmp                 { private header "__utility/cmp.h"                 }
+      module decay_copy          { private header "__utility/decay_copy.h"          }
       module declval             { private header "__utility/declval.h"             }
       module exchange            { private header "__utility/exchange.h"            }
       module forward             { private header "__utility/forward.h"             }
diff --git a/libcxx/include/thread b/libcxx/include/thread
--- a/libcxx/include/thread
+++ b/libcxx/include/thread
@@ -87,7 +87,7 @@
 #include <__functional_base>
 #include <__mutex_base>
 #include <__threading_support>
-#include <__utility/__decay_copy.h>
+#include <__utility/decay_copy.h>
 #include <__utility/forward.h>
 #include <chrono>
 #include <cstddef>
diff --git a/libcxx/test/libcxx/diagnostics/detail.headers/utility/__decay_copy.module.verify.cpp b/libcxx/test/libcxx/diagnostics/detail.headers/utility/decay_copy.module.verify.cpp
rename from libcxx/test/libcxx/diagnostics/detail.headers/utility/__decay_copy.module.verify.cpp
rename to libcxx/test/libcxx/diagnostics/detail.headers/utility/decay_copy.module.verify.cpp
--- a/libcxx/test/libcxx/diagnostics/detail.headers/utility/__decay_copy.module.verify.cpp
+++ b/libcxx/test/libcxx/diagnostics/detail.headers/utility/decay_copy.module.verify.cpp
@@ -12,5 +12,5 @@
 // WARNING: This test was generated by 'generate_private_header_tests.py'
 // and should not be edited manually.
 
-// expected-error@*:* {{use of private header from outside its module: '__utility/__decay_copy.h'}}
-#include <__utility/__decay_copy.h>
+// expected-error@*:* {{use of private header from outside its module: '__utility/decay_copy.h'}}
+#include <__utility/decay_copy.h>