diff --git a/libcxx/docs/ReleaseNotes/20.rst b/libcxx/docs/ReleaseNotes/20.rst
index c8a07fb8b7334..ecfbaa5b7a375 100644
--- a/libcxx/docs/ReleaseNotes/20.rst
+++ b/libcxx/docs/ReleaseNotes/20.rst
@@ -73,6 +73,39 @@ Improvements and New Features
   optimized, resulting in a performance improvement of up to 2x for trivial element types (e.g., `std::vector<int>`),
   and up to 3.4x for non-trivial element types (e.g., `std::vector<std::vector<int>>`).
 
+- On Windows, ``<system_error>``'s ``std::system_category`` is now distinct from ``std::generic_category``. The behavior
+  on other operating systems is unchanged.
+
+  On Windows -- unlike on Unix systems -- the libc and system APIs use distinct error codes. The libc functions return
+  ``errno.h`` error codes via the ``errno`` global, while Win32 API functions return ``winerror.h`` error codes via
+  ``GetLastError()``.
+
+  The C++ standard's ``std::error_code`` and ``std::error_category`` functionality was designed to support multiple
+  error domains, precisely in order to handle situations such as this. However, libc++ formerly treated
+  ``generic_category()`` and ``system_category()`` as equivalent, even on Windows. It now implements the intended split,
+  where ``system_category`` represents native ``winerror.h`` error codes, and ``generic_category`` represents libc error
+  codes (and, equivalently, ``std::errc::*`` errors).
+
+  This change enables code like ``std::error_code(GetLastError(), std::system_category()) ==
+  std::errc::invalid_argument`` to function as desired: constructing an ``error_code`` with the Windows error number in
+  the "system" category, and then mapping it to a generic code with ``error_condition``, for comparison with the
+  ``std::errc`` constant.
+
+  This is an incompatible change: ``std::error_code(ENOSYS, std::system_category()) ==
+  std::errc::function_not_supported`` would formerly have returned true, but now returns false on Windows. Code
+  providing a number from the ``errno.h`` domain should be migrated to construct a ``generic_category`` error_code,
+  instead. (E.g., use ``std::error_code(ENOSYS, std::generic_category())``). The new behavior matches MSVC.
+
+- On Windows, the ``std::filesystem`` library now returns the Win32 ``system_category`` error codes, where it's feasible
+  to do so. This allows interrogation and reporting of the original error code, which is useful if multiple Windows
+  errors map to a single generic error (such as with ``std::errc::no_such_file_or_directory``).
+
+  This is also a slightly-incompatible API change: code inspecting the raw integer value from the returned error_code
+  expecting an integer from ``generic_category`` (e.g. ``err.value() == ENOTDIR``) will not work as desired. Instead,
+  such code should use the comparison operators which implicitly handle eror mappings, ``err ==
+  std::errc::not_a_directory``, or use ``err.default_error_condition()`` to map to an ``error_condition``, and then test
+  its ``value()`` and ``category()``.
+
 Deprecations and Removals
 -------------------------
 
diff --git a/libcxx/include/__filesystem/directory_entry.h b/libcxx/include/__filesystem/directory_entry.h
index 7d0c01b98def6..11e07acdbe00c 100644
--- a/libcxx/include/__filesystem/directory_entry.h
+++ b/libcxx/include/__filesystem/directory_entry.h
@@ -22,7 +22,9 @@
 #include <__filesystem/perms.h>
 #include <__fwd/ostream.h>
 #include <__system_error/errc.h>
+#include <__system_error/error_category.h>
 #include <__system_error/error_code.h>
+#include <__system_error/error_condition.h>
 #include <__utility/move.h>
 #include <__utility/unreachable.h>
 #include <cstdint>
@@ -274,15 +276,7 @@ class directory_entry {
   _LIBCPP_EXPORTED_FROM_ABI error_code __do_refresh() noexcept;
 
   _LIBCPP_HIDE_FROM_ABI static bool __is_dne_error(error_code const& __ec) {
-    if (!__ec)
-      return true;
-    switch (static_cast<errc>(__ec.value())) {
-    case errc::no_such_file_or_directory:
-    case errc::not_a_directory:
-      return true;
-    default:
-      return false;
-    }
+    return !__ec || __ec == errc::no_such_file_or_directory || __ec == errc::not_a_directory;
   }
 
   _LIBCPP_HIDE_FROM_ABI void
diff --git a/libcxx/include/__system_error/system_error.h b/libcxx/include/__system_error/system_error.h
index 918effb6917cb..36ccf94cc010d 100644
--- a/libcxx/include/__system_error/system_error.h
+++ b/libcxx/include/__system_error/system_error.h
@@ -39,6 +39,10 @@ class _LIBCPP_EXPORTED_FROM_ABI system_error : public runtime_error {
   _LIBCPP_HIDE_FROM_ABI const error_code& code() const _NOEXCEPT { return __ec_; }
 };
 
+// __ev is expected to be an error in the generic_category domain (e.g. from
+// errno, or std::errc::*), not system_category (e.g. from windows syscalls).
+[[__noreturn__]] _LIBCPP_EXPORTED_FROM_ABI void __throw_system_error(int __ev, const char* __what_arg);
+
 [[__noreturn__]] _LIBCPP_HIDE_FROM_ABI inline void __throw_system_error(error_code __ec, const char* __what_arg) {
 #if _LIBCPP_HAS_EXCEPTIONS
   throw system_error(__ec, __what_arg);
diff --git a/libcxx/src/filesystem/directory_iterator.cpp b/libcxx/src/filesystem/directory_iterator.cpp
index d7ed9a358f559..7e8e40d17f7a0 100644
--- a/libcxx/src/filesystem/directory_iterator.cpp
+++ b/libcxx/src/filesystem/directory_iterator.cpp
@@ -47,9 +47,9 @@ class __dir_stream {
     }
     __stream_ = ::FindFirstFileW((root / "*").c_str(), &__data_);
     if (__stream_ == INVALID_HANDLE_VALUE) {
-      ec                                  = detail::make_windows_error(GetLastError());
+      ec                                  = detail::get_last_error();
       const bool ignore_permission_denied = bool(opts & directory_options::skip_permission_denied);
-      if (ignore_permission_denied && ec.value() == static_cast<int>(errc::permission_denied))
+      if (ignore_permission_denied && ec == errc::permission_denied)
         ec.clear();
       return;
     }
@@ -91,7 +91,7 @@ class __dir_stream {
   error_code close() noexcept {
     error_code ec;
     if (!::FindClose(__stream_))
-      ec = detail::make_windows_error(GetLastError());
+      ec = detail::get_last_error();
     __stream_ = INVALID_HANDLE_VALUE;
     return ec;
   }
@@ -118,7 +118,7 @@ class __dir_stream {
     if ((__stream_ = ::opendir(root.c_str())) == nullptr) {
       ec                      = detail::capture_errno();
       const bool allow_eacces = bool(opts & directory_options::skip_permission_denied);
-      if (allow_eacces && ec.value() == EACCES)
+      if (allow_eacces && ec == errc::permission_denied)
         ec.clear();
       return;
     }
@@ -307,7 +307,7 @@ bool recursive_directory_iterator::__try_recursion(error_code* ec) {
   }
   if (m_ec) {
     const bool allow_eacess = bool(__imp_->__options_ & directory_options::skip_permission_denied);
-    if (m_ec.value() == EACCES && allow_eacess) {
+    if (m_ec == errc::permission_denied && allow_eacess) {
       if (ec)
         ec->clear();
     } else {
diff --git a/libcxx/src/filesystem/error.h b/libcxx/src/filesystem/error.h
index 07ba7fc3eef25..c0213910b3780 100644
--- a/libcxx/src/filesystem/error.h
+++ b/libcxx/src/filesystem/error.h
@@ -32,80 +32,21 @@ _LIBCPP_BEGIN_NAMESPACE_FILESYSTEM
 
 namespace detail {
 
-#if defined(_LIBCPP_WIN32API)
-
-inline errc __win_err_to_errc(int err) {
-  constexpr struct {
-    DWORD win;
-    errc errc;
-  } win_error_mapping[] = {
-      {ERROR_ACCESS_DENIED, errc::permission_denied},
-      {ERROR_ALREADY_EXISTS, errc::file_exists},
-      {ERROR_BAD_NETPATH, errc::no_such_file_or_directory},
-      {ERROR_BAD_PATHNAME, errc::no_such_file_or_directory},
-      {ERROR_BAD_UNIT, errc::no_such_device},
-      {ERROR_BROKEN_PIPE, errc::broken_pipe},
-      {ERROR_BUFFER_OVERFLOW, errc::filename_too_long},
-      {ERROR_BUSY, errc::device_or_resource_busy},
-      {ERROR_BUSY_DRIVE, errc::device_or_resource_busy},
-      {ERROR_CANNOT_MAKE, errc::permission_denied},
-      {ERROR_CANTOPEN, errc::io_error},
-      {ERROR_CANTREAD, errc::io_error},
-      {ERROR_CANTWRITE, errc::io_error},
-      {ERROR_CURRENT_DIRECTORY, errc::permission_denied},
-      {ERROR_DEV_NOT_EXIST, errc::no_such_device},
-      {ERROR_DEVICE_IN_USE, errc::device_or_resource_busy},
-      {ERROR_DIR_NOT_EMPTY, errc::directory_not_empty},
-      {ERROR_DIRECTORY, errc::invalid_argument},
-      {ERROR_DISK_FULL, errc::no_space_on_device},
-      {ERROR_FILE_EXISTS, errc::file_exists},
-      {ERROR_FILE_NOT_FOUND, errc::no_such_file_or_directory},
-      {ERROR_HANDLE_DISK_FULL, errc::no_space_on_device},
-      {ERROR_INVALID_ACCESS, errc::permission_denied},
-      {ERROR_INVALID_DRIVE, errc::no_such_device},
-      {ERROR_INVALID_FUNCTION, errc::function_not_supported},
-      {ERROR_INVALID_HANDLE, errc::invalid_argument},
-      {ERROR_INVALID_NAME, errc::no_such_file_or_directory},
-      {ERROR_INVALID_PARAMETER, errc::invalid_argument},
-      {ERROR_LOCK_VIOLATION, errc::no_lock_available},
-      {ERROR_LOCKED, errc::no_lock_available},
-      {ERROR_NEGATIVE_SEEK, errc::invalid_argument},
-      {ERROR_NOACCESS, errc::permission_denied},
-      {ERROR_NOT_ENOUGH_MEMORY, errc::not_enough_memory},
-      {ERROR_NOT_READY, errc::resource_unavailable_try_again},
-      {ERROR_NOT_SAME_DEVICE, errc::cross_device_link},
-      {ERROR_NOT_SUPPORTED, errc::not_supported},
-      {ERROR_OPEN_FAILED, errc::io_error},
-      {ERROR_OPEN_FILES, errc::device_or_resource_busy},
-      {ERROR_OPERATION_ABORTED, errc::operation_canceled},
-      {ERROR_OUTOFMEMORY, errc::not_enough_memory},
-      {ERROR_PATH_NOT_FOUND, errc::no_such_file_or_directory},
-      {ERROR_READ_FAULT, errc::io_error},
-      {ERROR_REPARSE_TAG_INVALID, errc::invalid_argument},
-      {ERROR_RETRY, errc::resource_unavailable_try_again},
-      {ERROR_SEEK, errc::io_error},
-      {ERROR_SHARING_VIOLATION, errc::permission_denied},
-      {ERROR_TOO_MANY_OPEN_FILES, errc::too_many_files_open},
-      {ERROR_WRITE_FAULT, errc::io_error},
-      {ERROR_WRITE_PROTECT, errc::permission_denied},
-  };
-
-  for (const auto& pair : win_error_mapping)
-    if (pair.win == static_cast<DWORD>(err))
-      return pair.errc;
-  return errc::invalid_argument;
-}
-
-#endif // _LIBCPP_WIN32API
+// On windows, libc functions use errno, but system functions use GetLastError.
+// So, callers need to be careful which of these next functions they call!
 
 inline error_code capture_errno() {
   _LIBCPP_ASSERT_INTERNAL(errno != 0, "Expected errno to be non-zero");
   return error_code(errno, generic_category());
 }
 
+inline error_code get_last_error() {
 #if defined(_LIBCPP_WIN32API)
-inline error_code make_windows_error(int err) { return make_error_code(__win_err_to_errc(err)); }
+  return std::error_code(GetLastError(), std::system_category());
+#else
+  return capture_errno();
 #endif
+}
 
 template <class T>
 T error_value();
diff --git a/libcxx/src/filesystem/file_descriptor.h b/libcxx/src/filesystem/file_descriptor.h
index db66ad55bd4fb..9c279c451f28c 100644
--- a/libcxx/src/filesystem/file_descriptor.h
+++ b/libcxx/src/filesystem/file_descriptor.h
@@ -201,7 +201,7 @@ inline perms posix_get_perms(const StatT& st) noexcept { return static_cast<perm
 inline file_status create_file_status(error_code& m_ec, path const& p, const StatT& path_stat, error_code* ec) {
   if (ec)
     *ec = m_ec;
-  if (m_ec && (m_ec.value() == ENOENT || m_ec.value() == ENOTDIR)) {
+  if (m_ec && (m_ec == errc::no_such_file_or_directory || m_ec == errc::not_a_directory)) {
     return file_status(file_type::not_found);
   } else if (m_ec) {
     ErrorHandler<void> err("posix_stat", ec, &p);
@@ -236,7 +236,7 @@ inline file_status create_file_status(error_code& m_ec, path const& p, const Sta
 inline file_status posix_stat(path const& p, StatT& path_stat, error_code* ec) {
   error_code m_ec;
   if (detail::stat(p.c_str(), &path_stat) == -1)
-    m_ec = detail::capture_errno();
+    m_ec = detail::get_last_error();
   return create_file_status(m_ec, p, path_stat, ec);
 }
 
@@ -248,7 +248,7 @@ inline file_status posix_stat(path const& p, error_code* ec) {
 inline file_status posix_lstat(path const& p, StatT& path_stat, error_code* ec) {
   error_code m_ec;
   if (detail::lstat(p.c_str(), &path_stat) == -1)
-    m_ec = detail::capture_errno();
+    m_ec = detail::get_last_error();
   return create_file_status(m_ec, p, path_stat, ec);
 }
 
@@ -260,7 +260,7 @@ inline file_status posix_lstat(path const& p, error_code* ec) {
 // http://pubs.opengroup.org/onlinepubs/9699919799/functions/ftruncate.html
 inline bool posix_ftruncate(const FileDescriptor& fd, off_t to_size, error_code& ec) {
   if (detail::ftruncate(fd.fd, to_size) == -1) {
-    ec = capture_errno();
+    ec = get_last_error();
     return true;
   }
   ec.clear();
@@ -269,7 +269,7 @@ inline bool posix_ftruncate(const FileDescriptor& fd, off_t to_size, error_code&
 
 inline bool posix_fchmod(const FileDescriptor& fd, const StatT& st, error_code& ec) {
   if (detail::fchmod(fd.fd, st.st_mode) == -1) {
-    ec = capture_errno();
+    ec = get_last_error();
     return true;
   }
   ec.clear();
@@ -286,7 +286,7 @@ inline file_status FileDescriptor::refresh_status(error_code& ec) {
   m_stat   = {};
   error_code m_ec;
   if (detail::fstat(fd, &m_stat) == -1)
-    m_ec = capture_errno();
+    m_ec = get_last_error();
   m_status = create_file_status(m_ec, name, m_stat, &ec);
   return m_status;
 }
diff --git a/libcxx/src/filesystem/operations.cpp b/libcxx/src/filesystem/operations.cpp
index 208a55723d883..d9f130eb10c0c 100644
--- a/libcxx/src/filesystem/operations.cpp
+++ b/libcxx/src/filesystem/operations.cpp
@@ -100,7 +100,7 @@ path __canonical(path const& orig_p, error_code* ec) {
 #if (defined(_POSIX_VERSION) && _POSIX_VERSION >= 200112) || defined(_LIBCPP_WIN32API)
   std::unique_ptr<path::value_type, decltype(&::free)> hold(detail::realpath(p.c_str(), nullptr), &::free);
   if (hold.get() == nullptr)
-    return err.report(capture_errno());
+    return err.report(detail::get_last_error());
   return {hold.get()};
 #else
 #  if defined(__MVS__) && !defined(PATH_MAX)
@@ -110,7 +110,7 @@ path __canonical(path const& orig_p, error_code* ec) {
 #  endif
   path::value_type* ret;
   if ((ret = detail::realpath(p.c_str(), buff)) == nullptr)
-    return err.report(capture_errno());
+    return err.report(detail::get_last_error());
   return {ret};
 #endif
 }
@@ -505,9 +505,9 @@ bool __create_directory(const path& p, error_code* ec) {
   if (detail::mkdir(p.c_str(), static_cast<int>(perms::all)) == 0)
     return true;
 
-  if (errno != EEXIST)
-    return err.report(capture_errno());
-  error_code mec = capture_errno();
+  error_code mec = detail::get_last_error();
+  if (mec != errc::file_exists)
+    return err.report(mec);
   error_code ignored_ec;
   const file_status st = status(p, ignored_ec);
   if (!is_directory(st))
@@ -529,10 +529,10 @@ bool __create_directory(path const& p, path const& attributes, error_code* ec) {
   if (detail::mkdir(p.c_str(), attr_stat.st_mode) == 0)
     return true;
 
-  if (errno != EEXIST)
-    return err.report(capture_errno());
+  mec = detail::get_last_error();
+  if (mec != errc::file_exists)
+    return err.report(mec);
 
-  mec = capture_errno();
   error_code ignored_ec;
   st = status(p, ignored_ec);
   if (!is_directory(st))
@@ -543,19 +543,19 @@ bool __create_directory(path const& p, path const& attributes, error_code* ec) {
 void __create_directory_symlink(path const& from, path const& to, error_code* ec) {
   ErrorHandler<void> err("create_directory_symlink", ec, &from, &to);
   if (detail::symlink_dir(from.c_str(), to.c_str()) == -1)
-    return err.report(capture_errno());
+    return err.report(detail::get_last_error());
 }
 
 void __create_hard_link(const path& from, const path& to, error_code* ec) {
   ErrorHandler<void> err("create_hard_link", ec, &from, &to);
   if (detail::link(from.c_str(), to.c_str()) == -1)
-    return err.report(capture_errno());
+    return err.report(detail::get_last_error());
 }
 
 void __create_symlink(path const& from, path const& to, error_code* ec) {
   ErrorHandler<void> err("create_symlink", ec, &from, &to);
   if (detail::symlink_file(from.c_str(), to.c_str()) == -1)
-    return err.report(capture_errno());
+    return err.report(detail::get_last_error());
 }
 
 path __current_path(error_code* ec) {
@@ -598,7 +598,7 @@ path __current_path(error_code* ec) {
 
   unique_ptr<path::value_type, Deleter> hold(detail::getcwd(ptr, size), deleter);
   if (hold.get() == nullptr)
-    return err.report(capture_errno(), "call to getcwd failed");
+    return err.report(detail::get_last_error(), "call to getcwd failed");
 
   return {hold.get()};
 }
@@ -606,7 +606,7 @@ path __current_path(error_code* ec) {
 void __current_path(const path& p, error_code* ec) {
   ErrorHandler<void> err("current_path", ec, &p);
   if (detail::chdir(p.c_str()) == -1)
-    err.report(capture_errno());
+    err.report(detail::get_last_error());
 }
 
 bool __equivalent(const path& p1, const path& p2, error_code* ec) {
@@ -694,10 +694,10 @@ void __last_write_time(const path& p, file_time_type new_time, error_code* ec) {
     return err.report(errc::value_too_large);
   detail::WinHandle h(p.c_str(), FILE_WRITE_ATTRIBUTES, 0);
   if (!h)
-    return err.report(detail::make_windows_error(GetLastError()));
+    return err.report(detail::get_last_error());
   FILETIME last_write = timespec_to_filetime(ts);
   if (!SetFileTime(h, nullptr, nullptr, &last_write))
-    return err.report(detail::make_windows_error(GetLastError()));
+    return err.report(detail::get_last_error());
 #else
   error_code m_ec;
   array<TimeSpec, 2> tbuf;
@@ -755,7 +755,7 @@ void __permissions(const path& p, perms prms, perm_options opts, error_code* ec)
 #if defined(AT_SYMLINK_NOFOLLOW) && defined(AT_FDCWD)
   const int flags = set_sym_perms ? AT_SYMLINK_NOFOLLOW : 0;
   if (detail::fchmodat(AT_FDCWD, p.c_str(), real_perms, flags) == -1) {
-    return err.report(capture_errno());
+    return err.report(detail::get_last_error());
   }
 #else
   if (set_sym_perms)
@@ -783,14 +783,14 @@ path __read_symlink(const path& p, error_code* ec) {
 #else
   StatT sb;
   if (detail::lstat(p.c_str(), &sb) == -1) {
-    return err.report(capture_errno());
+    return err.report(detail::get_last_error());
   }
   const size_t size = sb.st_size + 1;
   auto buff         = unique_ptr<path::value_type[]>(new path::value_type[size]);
 #endif
   detail::SSizeT ret;
   if ((ret = detail::readlink(p.c_str(), buff.get(), size)) == -1)
-    return err.report(capture_errno());
+    return err.report(detail::get_last_error());
   // Note that `ret` returning `0` would work, resulting in a valid empty string being returned.
   if (static_cast<size_t>(ret) >= size)
     return err.report(errc::value_too_large);
@@ -801,8 +801,9 @@ path __read_symlink(const path& p, error_code* ec) {
 bool __remove(const path& p, error_code* ec) {
   ErrorHandler<bool> err("remove", ec, &p);
   if (detail::remove(p.c_str()) == -1) {
-    if (errno != ENOENT)
-      err.report(capture_errno());
+    error_code mec = detail::get_last_error();
+    if (mec != errc::no_such_file_or_directory)
+      err.report(mec);
     return false;
   }
   return true;
@@ -955,13 +956,13 @@ uintmax_t __remove_all(const path& p, error_code* ec) {
 void __rename(const path& from, const path& to, error_code* ec) {
   ErrorHandler<void> err("rename", ec, &from, &to);
   if (detail::rename(from.c_str(), to.c_str()) == -1)
-    err.report(capture_errno());
+    err.report(detail::get_last_error());
 }
 
 void __resize_file(const path& p, uintmax_t size, error_code* ec) {
   ErrorHandler<void> err("resize_file", ec, &p);
   if (detail::truncate(p.c_str(), static_cast< ::off_t>(size)) == -1)
-    return err.report(capture_errno());
+    return err.report(detail::get_last_error());
 }
 
 space_info __space(const path& p, error_code* ec) {
@@ -969,7 +970,7 @@ space_info __space(const path& p, error_code* ec) {
   space_info si;
   detail::StatVFS m_svfs = {};
   if (detail::statvfs(p.c_str(), &m_svfs) == -1) {
-    err.report(capture_errno());
+    err.report(detail::get_last_error());
     si.capacity = si.free = si.available = static_cast<uintmax_t>(-1);
     return si;
   }
@@ -996,7 +997,7 @@ path __temp_directory_path(error_code* ec) {
   wchar_t buf[MAX_PATH];
   DWORD retval = GetTempPathW(MAX_PATH, buf);
   if (!retval)
-    return err.report(detail::make_windows_error(GetLastError()));
+    return err.report(detail::get_last_error());
   if (retval > MAX_PATH)
     return err.report(errc::filename_too_long);
   // GetTempPathW returns a path with a trailing slash, which we
diff --git a/libcxx/src/filesystem/posix_compat.h b/libcxx/src/filesystem/posix_compat.h
index b41c004341af3..ddd99d8aaf206 100644
--- a/libcxx/src/filesystem/posix_compat.h
+++ b/libcxx/src/filesystem/posix_compat.h
@@ -11,9 +11,10 @@
 //
 // These generally behave like the proper posix functions, with these
 // exceptions:
-// On Windows, they take paths in wchar_t* form, instead of char* form.
-// The symlink() function is split into two frontends, symlink_file()
-// and symlink_dir().
+// - On Windows, they take paths in wchar_t* form, instead of char* form.
+// - The symlink() function is split into two frontends, symlink_file()
+//   and symlink_dir().
+// - Errors should be retrieved with get_last_error, not errno.
 //
 // These are provided within an anonymous namespace within the detail
 // namespace - callers need to include this header and call them as
@@ -122,11 +123,6 @@ namespace detail {
 
 #  define O_NONBLOCK 0
 
-inline int set_errno(int e = GetLastError()) {
-  errno = static_cast<int>(__win_err_to_errc(e));
-  return -1;
-}
-
 class WinHandle {
 public:
   WinHandle(const wchar_t* p, DWORD access, DWORD flags) {
@@ -153,7 +149,7 @@ class WinHandle {
 inline int stat_handle(HANDLE h, StatT* buf) {
   FILE_BASIC_INFO basic;
   if (!GetFileInformationByHandleEx(h, FileBasicInfo, &basic, sizeof(basic)))
-    return set_errno();
+    return -1;
   memset(buf, 0, sizeof(*buf));
   buf->st_mtim = filetime_to_timespec(basic.LastWriteTime);
   buf->st_atim = filetime_to_timespec(basic.LastAccessTime);
@@ -168,18 +164,18 @@ inline int stat_handle(HANDLE h, StatT* buf) {
   if (basic.FileAttributes & FILE_ATTRIBUTE_REPARSE_POINT) {
     FILE_ATTRIBUTE_TAG_INFO tag;
     if (!GetFileInformationByHandleEx(h, FileAttributeTagInfo, &tag, sizeof(tag)))
-      return set_errno();
+      return -1;
     if (tag.ReparseTag == IO_REPARSE_TAG_SYMLINK)
       buf->st_mode = (buf->st_mode & ~_S_IFMT) | _S_IFLNK;
   }
   FILE_STANDARD_INFO standard;
   if (!GetFileInformationByHandleEx(h, FileStandardInfo, &standard, sizeof(standard)))
-    return set_errno();
+    return -1;
   buf->st_nlink = standard.NumberOfLinks;
   buf->st_size  = standard.EndOfFile.QuadPart;
   BY_HANDLE_FILE_INFORMATION info;
   if (!GetFileInformationByHandle(h, &info))
-    return set_errno();
+    return -1;
   buf->st_dev = info.dwVolumeSerialNumber;
   memcpy(&buf->st_ino.id[0], &info.nFileIndexHigh, 4);
   memcpy(&buf->st_ino.id[4], &info.nFileIndexLow, 4);
@@ -189,7 +185,7 @@ inline int stat_handle(HANDLE h, StatT* buf) {
 inline int stat_file(const wchar_t* path, StatT* buf, DWORD flags) {
   WinHandle h(path, FILE_READ_ATTRIBUTES, flags);
   if (!h)
-    return set_errno();
+    return -1;
   int ret = stat_handle(h, buf);
   return ret;
 }
@@ -206,7 +202,7 @@ inline int fstat(int fd, StatT* buf) {
 inline int mkdir(const wchar_t* path, int permissions) {
   (void)permissions;
   if (!CreateDirectoryW(path, nullptr))
-    return set_errno();
+    return -1;
   return 0;
 }
 
@@ -219,10 +215,10 @@ inline int symlink_file_dir(const wchar_t* oldname, const wchar_t* newname, bool
     return 0;
   int e = GetLastError();
   if (e != ERROR_INVALID_PARAMETER)
-    return set_errno(e);
+    return -1;
   if (CreateSymbolicLinkW(newname, oldname, flags))
     return 0;
-  return set_errno();
+  return -1;
 }
 
 inline int symlink_file(const wchar_t* oldname, const wchar_t* newname) {
@@ -236,17 +232,17 @@ inline int symlink_dir(const wchar_t* oldname, const wchar_t* newname) {
 inline int link(const wchar_t* oldname, const wchar_t* newname) {
   if (CreateHardLinkW(newname, oldname, nullptr))
     return 0;
-  return set_errno();
+  return -1;
 }
 
 inline int remove(const wchar_t* path) {
   detail::WinHandle h(path, DELETE, FILE_FLAG_OPEN_REPARSE_POINT);
   if (!h)
-    return set_errno();
+    return -1;
   FILE_DISPOSITION_INFO info;
   info.DeleteFile = TRUE;
   if (!SetFileInformationByHandle(h, FileDispositionInfo, &info, sizeof(info)))
-    return set_errno();
+    return -1;
   return 0;
 }
 
@@ -254,9 +250,9 @@ inline int truncate_handle(HANDLE h, off_t length) {
   LARGE_INTEGER size_param;
   size_param.QuadPart = length;
   if (!SetFilePointerEx(h, size_param, 0, FILE_BEGIN))
-    return set_errno();
+    return -1;
   if (!SetEndOfFile(h))
-    return set_errno();
+    return -1;
   return 0;
 }
 
@@ -268,19 +264,19 @@ inline int ftruncate(int fd, off_t length) {
 inline int truncate(const wchar_t* path, off_t length) {
   detail::WinHandle h(path, GENERIC_WRITE, 0);
   if (!h)
-    return set_errno();
+    return -1;
   return truncate_handle(h, length);
 }
 
 inline int rename(const wchar_t* from, const wchar_t* to) {
   if (!(MoveFileExW(from, to, MOVEFILE_COPY_ALLOWED | MOVEFILE_REPLACE_EXISTING | MOVEFILE_WRITE_THROUGH)))
-    return set_errno();
+    return -1;
   return 0;
 }
 
 inline int chdir(const wchar_t* path) {
   if (!SetCurrentDirectoryW(path))
-    return set_errno();
+    return -1;
   return 0;
 }
 
@@ -300,7 +296,7 @@ inline int statvfs(const wchar_t* p, StatVFS* buf) {
       break;
     path parent = dir.parent_path();
     if (parent == dir) {
-      errno = ENOENT;
+      SetLastError(ERROR_PATH_NOT_FOUND);
       return -1;
     }
     dir = parent;
@@ -308,7 +304,7 @@ inline int statvfs(const wchar_t* p, StatVFS* buf) {
   ULARGE_INTEGER free_bytes_available_to_caller, total_number_of_bytes, total_number_of_free_bytes;
   if (!GetDiskFreeSpaceExW(
           dir.c_str(), &free_bytes_available_to_caller, &total_number_of_bytes, &total_number_of_free_bytes))
-    return set_errno();
+    return -1;
   buf->f_frsize = 1;
   buf->f_blocks = total_number_of_bytes.QuadPart;
   buf->f_bfree  = total_number_of_free_bytes.QuadPart;
@@ -330,7 +326,6 @@ inline wchar_t* getcwd([[maybe_unused]] wchar_t* in_buf, [[maybe_unused]] size_t
     retval = GetCurrentDirectoryW(buff_size, buff.get());
   }
   if (!retval) {
-    set_errno();
     return nullptr;
   }
   return buff.release();
@@ -342,7 +337,6 @@ inline wchar_t* realpath(const wchar_t* path, [[maybe_unused]] wchar_t* resolved
 
   WinHandle h(path, FILE_READ_ATTRIBUTES, 0);
   if (!h) {
-    set_errno();
     return nullptr;
   }
   size_t buff_size = MAX_PATH + 10;
@@ -354,7 +348,6 @@ inline wchar_t* realpath(const wchar_t* path, [[maybe_unused]] wchar_t* resolved
     retval = GetFinalPathNameByHandleW(h, buff.get(), buff_size, FILE_NAME_NORMALIZED | VOLUME_NAME_DOS);
   }
   if (!retval) {
-    set_errno();
     return nullptr;
   }
   wchar_t* ptr = buff.get();
@@ -376,20 +369,20 @@ using ModeT = int;
 inline int fchmod_handle(HANDLE h, int perms) {
   FILE_BASIC_INFO basic;
   if (!GetFileInformationByHandleEx(h, FileBasicInfo, &basic, sizeof(basic)))
-    return set_errno();
+    return -1;
   DWORD orig_attributes = basic.FileAttributes;
   basic.FileAttributes &= ~FILE_ATTRIBUTE_READONLY;
   if ((perms & 0222) == 0)
     basic.FileAttributes |= FILE_ATTRIBUTE_READONLY;
   if (basic.FileAttributes != orig_attributes && !SetFileInformationByHandle(h, FileBasicInfo, &basic, sizeof(basic)))
-    return set_errno();
+    return -1;
   return 0;
 }
 
 inline int fchmodat(int /*fd*/, const wchar_t* path, int perms, int flag) {
   DWORD attributes = GetFileAttributesW(path);
   if (attributes == INVALID_FILE_ATTRIBUTES)
-    return set_errno();
+    return -1;
   if (attributes & FILE_ATTRIBUTE_REPARSE_POINT && !(flag & AT_SYMLINK_NOFOLLOW)) {
     // If the file is a symlink, and we are supposed to operate on the target
     // of the symlink, we need to open a handle to it, without the
@@ -397,7 +390,7 @@ inline int fchmodat(int /*fd*/, const wchar_t* path, int perms, int flag) {
     // symlink, and operate on it via the handle.
     detail::WinHandle h(path, FILE_READ_ATTRIBUTES | FILE_WRITE_ATTRIBUTES, 0);
     if (!h)
-      return set_errno();
+      return -1;
     return fchmod_handle(h, perms);
   } else {
     // For a non-symlink, or if operating on the symlink itself instead of
@@ -407,7 +400,7 @@ inline int fchmodat(int /*fd*/, const wchar_t* path, int perms, int flag) {
     if ((perms & 0222) == 0)
       attributes |= FILE_ATTRIBUTE_READONLY;
     if (attributes != orig_attributes && !SetFileAttributesW(path, attributes))
-      return set_errno();
+      return -1;
   }
   return 0;
 }
@@ -424,18 +417,18 @@ inline SSizeT readlink(const wchar_t* path, wchar_t* ret_buf, size_t bufsize) {
   uint8_t buf[MAXIMUM_REPARSE_DATA_BUFFER_SIZE];
   detail::WinHandle h(path, FILE_READ_ATTRIBUTES, FILE_FLAG_OPEN_REPARSE_POINT);
   if (!h)
-    return set_errno();
+    return -1;
   DWORD out;
   if (!DeviceIoControl(h, FSCTL_GET_REPARSE_POINT, nullptr, 0, buf, sizeof(buf), &out, 0))
-    return set_errno();
+    return -1;
   const auto* reparse    = reinterpret_cast<LIBCPP_REPARSE_DATA_BUFFER*>(buf);
   size_t path_buf_offset = offsetof(LIBCPP_REPARSE_DATA_BUFFER, SymbolicLinkReparseBuffer.PathBuffer[0]);
   if (out < path_buf_offset) {
-    errno = EINVAL;
+    SetLastError(ERROR_REPARSE_TAG_INVALID);
     return -1;
   }
   if (reparse->ReparseTag != IO_REPARSE_TAG_SYMLINK) {
-    errno = EINVAL;
+    SetLastError(ERROR_REPARSE_TAG_INVALID);
     return -1;
   }
   const auto& symlink = reparse->SymbolicLinkReparseBuffer;
@@ -449,11 +442,11 @@ inline SSizeT readlink(const wchar_t* path, wchar_t* ret_buf, size_t bufsize) {
   }
   // name_offset/length are expressed in bytes, not in wchar_t
   if (path_buf_offset + name_offset + name_length > out) {
-    errno = EINVAL;
+    SetLastError(ERROR_REPARSE_TAG_INVALID);
     return -1;
   }
   if (name_length / sizeof(wchar_t) > bufsize) {
-    errno = ENOMEM;
+    SetLastError(ERROR_NOT_ENOUGH_MEMORY);
     return -1;
   }
   memcpy(ret_buf, &symlink.PathBuffer[name_offset / sizeof(wchar_t)], name_length);
diff --git a/libcxx/src/print.cpp b/libcxx/src/print.cpp
index 37b1fc00cd7c3..4937aafe84177 100644
--- a/libcxx/src/print.cpp
+++ b/libcxx/src/print.cpp
@@ -51,7 +51,7 @@ __write_to_windows_console([[maybe_unused]] FILE* __stream, [[maybe_unused]] wst
                     __view.size(),
                     nullptr,
                     nullptr) == 0) {
-    __throw_system_error(filesystem::detail::make_windows_error(GetLastError()), "failed to write formatted output");
+    __throw_system_error(filesystem::detail::get_last_error(), "failed to write formatted output");
   }
 }
 #  endif // _LIBCPP_HAS_WIDE_CHARACTERS
diff --git a/libcxx/src/system_error.cpp b/libcxx/src/system_error.cpp
index d555bca995c45..d5ec73084f638 100644
--- a/libcxx/src/system_error.cpp
+++ b/libcxx/src/system_error.cpp
@@ -14,6 +14,7 @@
 #include <cstdio>
 #include <cstdlib>
 #include <cstring>
+#include <optional>
 #include <string.h>
 #include <string>
 #include <system_error>
@@ -24,8 +25,123 @@
 #  include <android/api-level.h>
 #endif
 
+#if defined(_LIBCPP_WIN32API)
+#  include <windows.h>
+#  include <winerror.h>
+#endif
+
 _LIBCPP_BEGIN_NAMESPACE_STD
 
+#if defined(_LIBCPP_WIN32API)
+
+namespace {
+std::optional<errc> __win_err_to_errc(int err) {
+  switch (err) {
+  case ERROR_ACCESS_DENIED:
+    return errc::permission_denied;
+  case ERROR_ALREADY_EXISTS:
+    return errc::file_exists;
+  case ERROR_BAD_NETPATH:
+    return errc::no_such_file_or_directory;
+  case ERROR_BAD_PATHNAME:
+    return errc::no_such_file_or_directory;
+  case ERROR_BAD_UNIT:
+    return errc::no_such_device;
+  case ERROR_BROKEN_PIPE:
+    return errc::broken_pipe;
+  case ERROR_BUFFER_OVERFLOW:
+    return errc::filename_too_long;
+  case ERROR_BUSY:
+    return errc::device_or_resource_busy;
+  case ERROR_BUSY_DRIVE:
+    return errc::device_or_resource_busy;
+  case ERROR_CANNOT_MAKE:
+    return errc::permission_denied;
+  case ERROR_CANTOPEN:
+    return errc::io_error;
+  case ERROR_CANTREAD:
+    return errc::io_error;
+  case ERROR_CANTWRITE:
+    return errc::io_error;
+  case ERROR_CURRENT_DIRECTORY:
+    return errc::permission_denied;
+  case ERROR_DEV_NOT_EXIST:
+    return errc::no_such_device;
+  case ERROR_DEVICE_IN_USE:
+    return errc::device_or_resource_busy;
+  case ERROR_DIR_NOT_EMPTY:
+    return errc::directory_not_empty;
+  case ERROR_DIRECTORY:
+    return errc::invalid_argument;
+  case ERROR_DISK_FULL:
+    return errc::no_space_on_device;
+  case ERROR_FILE_EXISTS:
+    return errc::file_exists;
+  case ERROR_FILE_NOT_FOUND:
+    return errc::no_such_file_or_directory;
+  case ERROR_HANDLE_DISK_FULL:
+    return errc::no_space_on_device;
+  case ERROR_INVALID_ACCESS:
+    return errc::permission_denied;
+  case ERROR_INVALID_DRIVE:
+    return errc::no_such_device;
+  case ERROR_INVALID_FUNCTION:
+    return errc::function_not_supported;
+  case ERROR_INVALID_HANDLE:
+    return errc::invalid_argument;
+  case ERROR_INVALID_NAME:
+    return errc::no_such_file_or_directory;
+  case ERROR_INVALID_PARAMETER:
+    return errc::invalid_argument;
+  case ERROR_LOCK_VIOLATION:
+    return errc::no_lock_available;
+  case ERROR_LOCKED:
+    return errc::no_lock_available;
+  case ERROR_NEGATIVE_SEEK:
+    return errc::invalid_argument;
+  case ERROR_NOACCESS:
+    return errc::permission_denied;
+  case ERROR_NOT_ENOUGH_MEMORY:
+    return errc::not_enough_memory;
+  case ERROR_NOT_READY:
+    return errc::resource_unavailable_try_again;
+  case ERROR_NOT_SAME_DEVICE:
+    return errc::cross_device_link;
+  case ERROR_NOT_SUPPORTED:
+    return errc::not_supported;
+  case ERROR_OPEN_FAILED:
+    return errc::io_error;
+  case ERROR_OPEN_FILES:
+    return errc::device_or_resource_busy;
+  case ERROR_OPERATION_ABORTED:
+    return errc::operation_canceled;
+  case ERROR_OUTOFMEMORY:
+    return errc::not_enough_memory;
+  case ERROR_PATH_NOT_FOUND:
+    return errc::no_such_file_or_directory;
+  case ERROR_READ_FAULT:
+    return errc::io_error;
+  case ERROR_REPARSE_TAG_INVALID:
+    return errc::invalid_argument;
+  case ERROR_RETRY:
+    return errc::resource_unavailable_try_again;
+  case ERROR_SEEK:
+    return errc::io_error;
+  case ERROR_SHARING_VIOLATION:
+    return errc::permission_denied;
+  case ERROR_TOO_MANY_OPEN_FILES:
+    return errc::too_many_files_open;
+  case ERROR_WRITE_FAULT:
+    return errc::io_error;
+  case ERROR_WRITE_PROTECT:
+    return errc::permission_denied;
+  default:
+    return {};
+  }
+}
+} // namespace
+#endif
+
 namespace {
 #if _LIBCPP_HAS_THREADS
 
@@ -157,19 +273,52 @@ class _LIBCPP_HIDDEN __system_error_category : public __do_message {
 const char* __system_error_category::name() const noexcept { return "system"; }
 
 string __system_error_category::message(int ev) const {
-#ifdef _LIBCPP_ELAST
+#ifdef _LIBCPP_WIN32API
+  std::string result;
+  char* str               = nullptr;
+  unsigned long num_chars = ::FormatMessageA(
+      FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
+      nullptr,
+      ev,
+      0,
+      reinterpret_cast<char*>(&str),
+      0,
+      nullptr);
+  auto is_whitespace = [](char ch) { return ch == '\n' || ch == '\r' || ch == ' '; };
+  while (num_chars > 0 && is_whitespace(str[num_chars - 1]))
+    --num_chars;
+
+  if (num_chars)
+    result = std::string(str, num_chars);
+  else
+    result = "Unknown error";
+
+  LocalFree(str);
+  return result;
+#else
+#  ifdef _LIBCPP_ELAST
   if (ev > _LIBCPP_ELAST)
     return string("unspecified system_category error");
-#endif // _LIBCPP_ELAST
+#  endif // _LIBCPP_ELAST
   return __do_message::message(ev);
+#endif
 }
 
 error_condition __system_error_category::default_error_condition(int ev) const noexcept {
-#ifdef _LIBCPP_ELAST
+#ifdef _LIBCPP_WIN32API
+  // Remap windows error codes to generic error codes if possible.
+  if (ev == 0)
+    return error_condition(0, generic_category());
+  if (auto maybe_errc = __win_err_to_errc(ev))
+    return error_condition(static_cast<int>(*maybe_errc), generic_category());
+  return error_condition(ev, system_category());
+#else
+#  ifdef _LIBCPP_ELAST
   if (ev > _LIBCPP_ELAST)
     return error_condition(ev, system_category());
-#endif // _LIBCPP_ELAST
+#  endif // _LIBCPP_ELAST
   return error_condition(ev, generic_category());
+#endif
 }
 
 const error_category& system_category() noexcept {
@@ -213,7 +362,7 @@ system_error::~system_error() noexcept {}
 
 void __throw_system_error(int ev, const char* what_arg) {
 #if _LIBCPP_HAS_EXCEPTIONS
-  std::__throw_system_error(error_code(ev, system_category()), what_arg);
+  std::__throw_system_error(error_code(ev, generic_category()), what_arg);
 #else
   // The above could also handle the no-exception case, but for size, avoid referencing system_category() unnecessarily.
   _LIBCPP_VERBOSE_ABORT(
diff --git a/libcxx/test/libcxx/diagnostics/system_error_win_codes.pass.cpp b/libcxx/test/libcxx/diagnostics/system_error_win_codes.pass.cpp
new file mode 100644
index 0000000000000..799a5b5c0b086
--- /dev/null
+++ b/libcxx/test/libcxx/diagnostics/system_error_win_codes.pass.cpp
@@ -0,0 +1,25 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: windows
+
+// Validate that system_error on windows accepts Windows' System Error Codes (as
+// used by win32 APIs and reported by GetLastError), and that they are properly
+// translated to generic conditions.
+
+#include <windows.h>
+#include <system_error>
+#include <cassert>
+
+#include "test_macros.h"
+
+int main(int, char**) {
+  LIBCPP_ASSERT(std::error_code(ERROR_ACCESS_DENIED, std::system_category()) == std::errc::permission_denied);
+  LIBCPP_ASSERT(std::error_code(ERROR_PATH_NOT_FOUND, std::system_category()) == std::errc::no_such_file_or_directory);
+  return 0;
+}
diff --git a/libcxx/test/std/diagnostics/syserr/syserr.compare/eq_error_code_error_code.pass.cpp b/libcxx/test/std/diagnostics/syserr/syserr.compare/eq_error_code_error_code.pass.cpp
index f1f49733280b1..a8b565bb0ab94 100644
--- a/libcxx/test/std/diagnostics/syserr/syserr.compare/eq_error_code_error_code.pass.cpp
+++ b/libcxx/test/std/diagnostics/syserr/syserr.compare/eq_error_code_error_code.pass.cpp
@@ -22,6 +22,10 @@
 
 #include "test_macros.h"
 
+#ifndef _WIN32
+#  define TEST_SYSTEM_CATEGORY_IS_GENERIC_CATEGORY
+#endif
+
 int main(int, char**) {
   std::error_code e_code1(5, std::generic_category());
   std::error_code e_code2(5, std::system_category());
@@ -45,7 +49,9 @@ int main(int, char**) {
   assert(e_code2 == e_code2);
   assert(e_code2 != e_code3);
   assert(e_code2 != e_code4);
+#ifdef TEST_SYSTEM_CATEGORY_IS_GENERIC_CATEGORY
   LIBCPP_ASSERT(e_code2 == e_condition1);
+#endif
   assert(e_code2 == e_condition2);
   LIBCPP_ASSERT(e_code2 != e_condition3);
   assert(e_code2 != e_condition4);
@@ -65,11 +71,15 @@ int main(int, char**) {
   assert(e_code4 == e_code4);
   LIBCPP_ASSERT(e_code4 != e_condition1);
   assert(e_code4 != e_condition2);
+#ifdef TEST_SYSTEM_CATEGORY_IS_GENERIC_CATEGORY
   LIBCPP_ASSERT(e_code4 == e_condition3);
+#endif
   assert(e_code4 == e_condition4);
 
   assert(e_condition1 == e_code1);
+#ifdef TEST_SYSTEM_CATEGORY_IS_GENERIC_CATEGORY
   LIBCPP_ASSERT(e_condition1 == e_code2);
+#endif
   assert(e_condition1 != e_code3);
   LIBCPP_ASSERT(e_condition1 != e_code4);
   assert(e_condition1 == e_condition1);
@@ -89,7 +99,9 @@ int main(int, char**) {
   assert(e_condition3 != e_code1);
   LIBCPP_ASSERT(e_condition3 != e_code2);
   assert(e_condition3 == e_code3);
+#ifdef TEST_SYSTEM_CATEGORY_IS_GENERIC_CATEGORY
   LIBCPP_ASSERT(e_condition3 == e_code4);
+#endif
   assert(e_condition3 != e_condition1);
   assert(e_condition3 != e_condition2);
   assert(e_condition3 == e_condition3);
diff --git a/libcxx/test/std/diagnostics/syserr/syserr.errcat/syserr.errcat.derived/message.pass.cpp b/libcxx/test/std/diagnostics/syserr/syserr.errcat/syserr.errcat.derived/message.pass.cpp
index 9f7eb42bc78d9..f7f43132902f6 100644
--- a/libcxx/test/std/diagnostics/syserr/syserr.errcat/syserr.errcat.derived/message.pass.cpp
+++ b/libcxx/test/std/diagnostics/syserr/syserr.errcat/syserr.errcat.derived/message.pass.cpp
@@ -29,8 +29,11 @@ int main(int, char**) {
   assert(!m1.empty());
   assert(!m2.empty());
   assert(!m3.empty());
+#ifndef _WIN32
+  // On windows, system_category is distinct.
   LIBCPP_ASSERT(m1 == m2);
-  assert(m1 != m3);
+#endif
+  assert(m2 != m3);
 
   return 0;
 }
diff --git a/libcxx/test/std/diagnostics/syserr/syserr.errcat/syserr.errcat.objects/system_category.pass.cpp b/libcxx/test/std/diagnostics/syserr/syserr.errcat/syserr.errcat.objects/system_category.pass.cpp
index 6ba33ba44ca4c..255cbe75e2fa9 100644
--- a/libcxx/test/std/diagnostics/syserr/syserr.errcat/syserr.errcat.objects/system_category.pass.cpp
+++ b/libcxx/test/std/diagnostics/syserr/syserr.errcat/syserr.errcat.objects/system_category.pass.cpp
@@ -33,7 +33,12 @@ int main(int, char**) {
   {
     const std::error_category& e_cat1 = std::system_category();
     std::error_condition e_cond       = e_cat1.default_error_condition(5);
+#ifdef _WIN32
+    // Windows' system error 5 is ERROR_ACCESS_DENIED, which maps to generic code permission_denied.
+    LIBCPP_ASSERT(e_cond.value() == static_cast<int>(std::errc::permission_denied));
+#else
     LIBCPP_ASSERT(e_cond.value() == 5);
+#endif
     LIBCPP_ASSERT(e_cond.category() == std::generic_category());
     assert(e_cat1.equivalent(5, e_cond));
 
diff --git a/libcxx/test/std/input.output/filesystems/class.directory_entry/directory_entry.obs/file_type_obs.pass.cpp b/libcxx/test/std/input.output/filesystems/class.directory_entry/directory_entry.obs/file_type_obs.pass.cpp
index 303a95a0128bc..071ee7f6c891f 100644
--- a/libcxx/test/std/input.output/filesystems/class.directory_entry/directory_entry.obs/file_type_obs.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.directory_entry/directory_entry.obs/file_type_obs.pass.cpp
@@ -172,8 +172,13 @@ static void test_with_ec_dne() {
     file_status st = status(p, status_ec);
     file_status sym_st = symlink_status(p, sym_status_ec);
     std::error_code ec = GetTestEC(2);
-    auto CheckEC = [&](std::error_code const& other_ec) {
-      bool res = ec == other_ec;
+    auto CheckEC                  = [&](std::error_code const& other_ec) {
+      // Note: we're comparing equality of the _canonicalized_ error_condition
+      // here (unlike in other tests where we expect exactly the same
+      // error_code). This is because directory_entry can construct its own
+      // generic_category error when a file doesn't exist, instead of passing
+      // through an underlying system_category error.
+      bool res = ec.default_error_condition() == other_ec.default_error_condition();
       ec = GetTestEC(2);
       return res;
     };
diff --git a/libcxx/test/std/input.output/filesystems/class.directory_entry/directory_entry.obs/status.pass.cpp b/libcxx/test/std/input.output/filesystems/class.directory_entry/directory_entry.obs/status.pass.cpp
index dd72232ee530a..dec04df7ca019 100644
--- a/libcxx/test/std/input.output/filesystems/class.directory_entry/directory_entry.obs/status.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.directory_entry/directory_entry.obs/status.pass.cpp
@@ -44,7 +44,7 @@ static void test_basic() {
     file_status es = e.status(eec);
     assert(ps.type() == es.type());
     assert(ps.permissions() == es.permissions());
-    assert(pec == eec);
+    assert(pec.default_error_condition() == eec.default_error_condition());
   }
   for (const auto& p : TestCases) {
     const directory_entry e(p);
diff --git a/libcxx/test/std/input.output/filesystems/class.directory_entry/directory_entry.obs/symlink_status.pass.cpp b/libcxx/test/std/input.output/filesystems/class.directory_entry/directory_entry.obs/symlink_status.pass.cpp
index 24e8069509527..77da936382aa2 100644
--- a/libcxx/test/std/input.output/filesystems/class.directory_entry/directory_entry.obs/symlink_status.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.directory_entry/directory_entry.obs/symlink_status.pass.cpp
@@ -44,7 +44,7 @@ static void test_signature() {
     file_status es = e.symlink_status(eec);
     assert(ps.type() == es.type());
     assert(ps.permissions() == es.permissions());
-    assert(pec == eec);
+    assert(pec.default_error_condition() == eec.default_error_condition());
   }
   for (const auto& p : TestCases) {
     const directory_entry e(p);
diff --git a/libcxx/test/support/filesystem_test_helper.h b/libcxx/test/support/filesystem_test_helper.h
index a63d645d1a01a..2ad9efb32c60f 100644
--- a/libcxx/test/support/filesystem_test_helper.h
+++ b/libcxx/test/support/filesystem_test_helper.h
@@ -583,7 +583,11 @@ struct ExceptionChecker {
     assert(ErrorIsImp(Err.code(), {expected_err}));
     assert(Err.path1() == expected_path1);
     assert(Err.path2() == expected_path2);
+#ifndef _WIN32
+    // On Windows, the error strings are windows error code strings, and don't
+    // match textually with the strings generated for generic std::errc::*.
     LIBCPP_ONLY(check_libcxx_string(Err));
+#endif
   }
 
   void check_libcxx_string(fs::filesystem_error const& Err) {