diff --git a/libcxx/include/__config b/libcxx/include/__config
--- a/libcxx/include/__config
+++ b/libcxx/include/__config
@@ -321,6 +321,15 @@
 #    define _LIBCPP_SHORT_WCHAR 1
 #  endif
 
+#  if _LIBCPP_ABI_VERSION < 2
+#    if defined(_AIX) || (defined(__MVS__) && defined(__64BIT__))
+#      define _LIBCPP_BASIC_IOS_HAS_FILL_SET 1
+#    elif defined(_WIN32) || defined(__sun__) || || defined(__APPLE__) || defined(__linux__) ||                        \
+          defined(__FreeBSD__) || defined(__NetBSD__)
+#      define _LIBCPP_BASIC_IOS_HAS_FILL_SET 0
+#    endif
+#  endif
+
 // Libc++ supports various implementations of std::random_device.
 //
 // _LIBCPP_USING_DEV_RANDOM
diff --git a/libcxx/include/ios b/libcxx/include/ios
--- a/libcxx/include/ios
+++ b/libcxx/include/ios
@@ -686,7 +686,15 @@
     void set_rdbuf(basic_streambuf<char_type, traits_type>* __sb);
 private:
     basic_ostream<char_type, traits_type>* __tie_;
+  
+#if defined(_LIBCPP_BASIC_IOS_HAS_FILL_SET)
+    static const bool __has_fill_set = _LIBCPP_BASIC_IOS_HAS_FILL_SET;
+#else
+    static const bool __has_fill_set = sizeof(char_type) >= sizeof(int_type);
+#endif
+
     mutable int_type __fill_;
+    mutable bool __fill_set_[__has_fill_set];
 };
 
 template <class _CharT, class _Traits>
@@ -708,7 +716,14 @@
 {
     ios_base::init(__sb);
     __tie_ = nullptr;
-    __fill_ = traits_type::eof();
+    if (__has_fill_set) 
+    {
+        __fill_set_[0] = false;
+    }
+    else
+    {
+        __fill_ = traits_type::eof();
+    }
 }
 
 template <class _CharT, class _Traits>
@@ -780,8 +795,18 @@
 _CharT
 basic_ios<_CharT, _Traits>::fill() const
 {
-    if (traits_type::eq_int_type(traits_type::eof(), __fill_))
+    if (__has_fill_set)
+    {
+        if (!__fill_set_[0])
+        {
+            __fill_ = widen(' ');
+            __fill_set_[0] = true;
+        }
+    }
+    else if (traits_type::eq_int_type(traits_type::eof(), __fill_))
+    {
         __fill_ = widen(' ');
+    }
     return __fill_;
 }
 
@@ -790,9 +815,7 @@
 _CharT
 basic_ios<_CharT, _Traits>::fill(char_type __ch)
 {
-    if (traits_type::eq_int_type(traits_type::eof(), __fill_))
-        __fill_ = widen(' ');
-    char_type __r = __fill_;
+    char_type __r = fill();
     __fill_ = __ch;
     return __r;
 }
@@ -807,6 +830,10 @@
         ios_base::copyfmt(__rhs);
         __tie_ = __rhs.__tie_;
         __fill_ = __rhs.__fill_;
+        if (__has_fill_set)
+        {
+            __fill_set_[0] = __rhs.__fill_set_[0];
+        }
         __call_callbacks(copyfmt_event);
         exceptions(__rhs.exceptions());
     }
@@ -822,6 +849,10 @@
     __tie_ = __rhs.__tie_;
     __rhs.__tie_ = nullptr;
     __fill_ = __rhs.__fill_;
+    if (__has_fill_set)
+    {
+        __fill_set_[0] = __rhs.__fill_set_[0];
+    }
 }
 
 template <class _CharT, class _Traits>
@@ -832,6 +863,10 @@
     ios_base::swap(__rhs);
     _VSTD::swap(__tie_, __rhs.__tie_);
     _VSTD::swap(__fill_, __rhs.__fill_);
+    if (__has_fill_set)
+    {
+        _VSTD::swap(__fill_set_[0], __rhs.__fill_set_[0]);
+    }
 }
 
 template <class _CharT, class _Traits>
diff --git a/libcxx/test/std/input.output/iostream.format/std.manip/setfill_eof.pass.cpp b/libcxx/test/std/input.output/iostream.format/std.manip/setfill_eof.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/input.output/iostream.format/std.manip/setfill_eof.pass.cpp
@@ -0,0 +1,40 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: no-wide-characters
+
+// XFAIL: stdlib=libc++ && target=aarch64-linux-gnu
+// XFAIL: stdlib=libc++ && target=armv7l-linux-gnueabihf
+// XFAIL: stdlib=libc++ && target=armv8l-linux-gnueabihf
+// XFAIL: stdlib=libc++ && target=x86_64-pc-windows-msvc
+// XFAIL: stdlib=libc++ && target=x86_64-w64-windows-gnu
+
+// <iomanip>
+
+// template<charT> unspecified setfill(charT c);
+
+#include <iomanip>
+#include <ostream>
+#include <cassert>
+#include <string>
+
+#include "test_macros.h"
+
+template <class CharT>
+struct testbuf : public std::basic_streambuf<CharT> {
+  testbuf() {}
+};
+
+int main(int, char**) {
+  testbuf<wchar_t> sb;
+  std::wostream os(&sb);
+  os << std::setfill((wchar_t)std::char_traits<wchar_t>::eof());
+  assert(os.fill() == (wchar_t)std::char_traits<wchar_t>::eof());
+
+  return 0;
+}