diff --git a/Doc/library/sys.rst b/Doc/library/sys.rst
index 2bdfb337f02056..40c582f04e90bd 100644
--- a/Doc/library/sys.rst
+++ b/Doc/library/sys.rst
@@ -13,8 +13,8 @@ always available. Unless explicitly noted otherwise, all variables are read-only
 
 .. data:: abiflags
 
-   On POSIX systems where Python was built with the standard ``configure``
-   script, this contains the ABI flags as specified by :pep:`3149`.
+   On POSIX and Windows systems where Python was built with the standard
+   ``configure`` script, this contains the ABI flags as specified by :pep:`3149`.
 
    .. versionadded:: 3.2
 
@@ -22,7 +22,10 @@ always available. Unless explicitly noted otherwise, all variables are read-only
       Default flags became an empty string (``m`` flag for pymalloc has been
       removed).
 
-   .. availability:: Unix.
+   .. versionchanged:: 3.14
+      The attribute was also added on Windows.
+
+   .. availability:: Unix, Windows.
 
 
 .. function:: addaudithook(hook)
diff --git a/Lib/test/test_sys.py b/Lib/test/test_sys.py
index 87c0106ad30840..8be5832819c5f1 100644
--- a/Lib/test/test_sys.py
+++ b/Lib/test/test_sys.py
@@ -696,8 +696,7 @@ def test_attributes(self):
         self.assertTrue(vi > (1,0,0))
         self.assertIsInstance(sys.float_repr_style, str)
         self.assertIn(sys.float_repr_style, ('short', 'legacy'))
-        if not sys.platform.startswith('win'):
-            self.assertIsInstance(sys.abiflags, str)
+        self.assertIsInstance(sys.abiflags, str)
 
     def test_thread_info(self):
         info = sys.thread_info
diff --git a/Misc/ACKS b/Misc/ACKS
index b0b4ea0db44b64..e7a7bac5ca151e 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -1402,6 +1402,7 @@ Todd R. Palmer
 Juan David Ibáñez Palomar
 Nicola Palumbo
 Jan Palus
+Xuehai Pan
 Yongzhi Pan
 Martin Panter
 Mathias Panzenböck
diff --git a/Misc/NEWS.d/next/Windows/2024-11-30-13-36-44.gh-issue-127405.gLRZoT.rst b/Misc/NEWS.d/next/Windows/2024-11-30-13-36-44.gh-issue-127405.gLRZoT.rst
new file mode 100644
index 00000000000000..ed067cb7259d9f
--- /dev/null
+++ b/Misc/NEWS.d/next/Windows/2024-11-30-13-36-44.gh-issue-127405.gLRZoT.rst
@@ -0,0 +1 @@
+Set :data:`sys.abiflags` on Windows. Patch by Xuehai Pan.
diff --git a/PC/pyconfig.h.in b/PC/pyconfig.h.in
index 9e70303868e5de..874479bffd67d3 100644
--- a/PC/pyconfig.h.in
+++ b/PC/pyconfig.h.in
@@ -102,6 +102,24 @@ WIN32 is still required for the locale module.
 /* #define Py_GIL_DISABLED 1 */
 #endif
 
+/* Defined in debug builds */
+#ifdef _DEBUG
+#  define Py_DEBUG
+#endif
+
+#ifdef Py_GIL_DISABLED
+#  define _ABIFLAGS_FREETHREADED "t"
+#else
+#  define _ABIFLAGS_FREETHREADED ""
+#endif
+#ifdef Py_DEBUG
+#  define _ABIFLAGS_DEBUG "d"
+#else
+#  define _ABIFLAGS_DEBUG ""
+#endif
+/* Set value for `sys.abiflags` */
+#define ABIFLAGS ("" _ABIFLAGS_FREETHREADED _ABIFLAGS_DEBUG)
+
 /* Compiler specific defines */
 
 /* ------------------------------------------------------------------------*/
@@ -319,21 +337,21 @@ Py_NO_ENABLE_SHARED to find out.  Also support MS_NO_COREDLL for b/w compat */
                         This is relevant when using build-system generator (e.g CMake) where
                         the linking is explicitly handled */
 #                       if defined(Py_GIL_DISABLED)
-#                       if defined(_DEBUG)
+#                       if defined(Py_DEBUG)
 #                               pragma comment(lib,"python314t_d.lib")
 #                       elif defined(Py_LIMITED_API)
 #                               pragma comment(lib,"python3t.lib")
 #                       else
 #                               pragma comment(lib,"python314t.lib")
-#                       endif /* _DEBUG */
+#                       endif /* Py_DEBUG */
 #                       else /* Py_GIL_DISABLED */
-#                       if defined(_DEBUG)
+#                       if defined(Py_DEBUG)
 #                               pragma comment(lib,"python314_d.lib")
 #                       elif defined(Py_LIMITED_API)
 #                               pragma comment(lib,"python3.lib")
 #                       else
 #                               pragma comment(lib,"python314.lib")
-#                       endif /* _DEBUG */
+#                       endif /* Py_DEBUG */
 #                       endif /* Py_GIL_DISABLED */
 #               endif /* _MSC_VER && !Py_NO_LINK_LIB */
 #       endif /* Py_BUILD_CORE */
@@ -376,11 +394,6 @@ Py_NO_ENABLE_SHARED to find out.  Also support MS_NO_COREDLL for b/w compat */
 #       define ALIGNOF_MAX_ALIGN_T 8
 #endif
 
-#ifdef _DEBUG
-#       define Py_DEBUG
-#endif
-
-
 #ifdef MS_WIN32
 
 #define SIZEOF_SHORT 2