diff --git a/newlib/libc/locale/locale.c b/newlib/libc/locale/locale.c
index e58ba3dbe..3772106e3 100644
--- a/newlib/libc/locale/locale.c
+++ b/newlib/libc/locale/locale.c
@@ -65,8 +65,8 @@ build with multibyte support and support for all ISO and Windows Codepage.
 Otherwise all singlebyte charsets are simply mapped to ASCII.  Right now,
 only newlib for Cygwin is built with full charset support by default.
 Under Cygwin, this implementation additionally supports the charsets
-<<"GBK">>, <<"GB2312">>, <<"eucCN">>, <<"eucKR">>, and <<"Big5">>.  Cygwin
-does not support <<"JIS">>.
+<<"GB18030">>, <<"GBK">>, <<"GB2312">>, <<"eucCN">>, <<"eucKR">>, and
+<<"Big5">>.  Cygwin does not support <<"JIS">>.
 
 Cygwin additionally supports locales from the file
 /usr/share/locale/locale.alias.
@@ -657,7 +657,7 @@ restart:
 	}
 #ifdef __CYGWIN__
       /* Newlib does neither provide EUC-KR nor EUC-CN, and Cygwin's
-      	 implementation requires Windows support. */
+	 implementation requires Windows support. */
       else if (!strcasecmp (c, "KR"))
 	{
 	  strcpy (charset, "EUCKR");
@@ -817,12 +817,19 @@ restart:
 	 requires Windows support. */
       if (!strcasecmp (charset, "GBK")
 	  || !strcasecmp (charset, "GB2312"))
-      	{
+	{
 	  strcpy (charset, charset[2] == '2' ? "GB2312" : "GBK");
 	  mbc_max = 2;
 	  l_wctomb = __gbk_wctomb;
 	  l_mbtowc = __gbk_mbtowc;
 	}
+      else if (!strcasecmp (charset, "GB18030"))
+	{
+	  strcpy (charset, "GB18030");
+	  mbc_max = 4;
+	  l_wctomb = __gb18030_wctomb;
+	  l_mbtowc = __gb18030_mbtowc;
+	}
       else
 #endif /* __CYGWIN__ */
       /* GEORGIAN-PS and the alias without dash */
diff --git a/newlib/libc/stdlib/local.h b/newlib/libc/stdlib/local.h
index a96ed2cc4..26fd4f05d 100644
--- a/newlib/libc/stdlib/local.h
+++ b/newlib/libc/stdlib/local.h
@@ -24,6 +24,7 @@ wctomb_p __iso_wctomb (int val);
 wctomb_p __cp_wctomb (int val);
 #ifdef __CYGWIN__
 wctomb_f __gbk_wctomb;
+wctomb_f __gb18030_wctomb;
 wctomb_f __kr_wctomb;
 wctomb_f __big5_wctomb;
 #endif
@@ -45,6 +46,7 @@ mbtowc_p __iso_mbtowc (int val);
 mbtowc_p __cp_mbtowc (int val);
 #ifdef __CYGWIN__
 mbtowc_f __gbk_mbtowc;
+mbtowc_f __gb18030_mbtowc;
 mbtowc_f __kr_mbtowc;
 mbtowc_f __big5_mbtowc;
 #endif
diff --git a/winsup/cygwin/fhandler/proc.cc b/winsup/cygwin/fhandler/proc.cc
index bb32d6498..d5e3c60fc 100644
--- a/winsup/cygwin/fhandler/proc.cc
+++ b/winsup/cygwin/fhandler/proc.cc
@@ -2323,6 +2323,7 @@ format_proc_codesets (void *, char *&destbuf)
 			 "EUC-CN\n"
 			 "EUC-JP\n"
 			 "EUC-KR\n"
+			 "GB18030\n"
 			 "GB2312\n"
 			 "GBK\n"
 			 "GEORGIAN-PS\n"
diff --git a/winsup/cygwin/nlsfuncs.cc b/winsup/cygwin/nlsfuncs.cc
index 95e291a28..808bf6a87 100644
--- a/winsup/cygwin/nlsfuncs.cc
+++ b/winsup/cygwin/nlsfuncs.cc
@@ -1578,8 +1578,8 @@ __eval_codepage_from_internal_charset ()
 	  break;
 	}
       break;
-    case 'G': /* GBK/GB2312 */
-      codepage = 936;
+    case 'G': /* GBK/GB2312/GB18030 */
+      codepage = (charset[2] == '1') ? 54936 : 936;
       break;
     case 'I': /* ISO-8859-x */
       codepage = strtoul (charset + 9, NULL, 10) + 28590;
diff --git a/winsup/cygwin/release/3.5.0 b/winsup/cygwin/release/3.5.0
index d6b24e5f9..4123b8d32 100644
--- a/winsup/cygwin/release/3.5.0
+++ b/winsup/cygwin/release/3.5.0
@@ -21,3 +21,5 @@ What's new:
   supported codesets and locales for all interested parties.  Locale(1)
   opens these files and uses the info for printing locale info like any
   other process could do.
+
+- Add support for GB18030 codeset.
diff --git a/winsup/cygwin/strfuncs.cc b/winsup/cygwin/strfuncs.cc
index 9324e1553..57abf2564 100644
--- a/winsup/cygwin/strfuncs.cc
+++ b/winsup/cygwin/strfuncs.cc
@@ -245,7 +245,8 @@ mbsnrtowci(wint_t *dst, const char **src, size_t nms, size_t len, mbstate_t *ps)
    eucJP, the both most used Japanese charset encodings, this shouldn't
    be such a big problem. */
 
-/* GBK, eucKR, and Big5 conversions are not available so far in newlib. */
+/* GBK, GB18030, eucKR, and Big5 conversions are not available so far
+   in newlib. */
 
 static int
 __db_wctomb (struct _reent *r, char *s, wchar_t wchar, UINT cp)
@@ -325,6 +326,12 @@ __gbk_wctomb (struct _reent *r, char *s, wchar_t wchar, mbstate_t *state)
   return __db_wctomb (r,s, wchar, 936);
 }
 
+extern "C" int
+__gb18030_wctomb (struct _reent *r, char *s, wchar_t wchar, mbstate_t *state)
+{
+  return __db_wctomb (r,s, wchar, 54936);
+}
+
 extern "C" int
 __kr_wctomb (struct _reent *r, char *s, wchar_t wchar, mbstate_t *state)
 {
@@ -482,6 +489,13 @@ __gbk_mbtowc (struct _reent *r, wchar_t *pwc, const char *s, size_t n,
   return __db_mbtowc (r, pwc, s, n, 936, state);
 }
 
+extern "C" int
+__gb18030_mbtowc (struct _reent *r, wchar_t *pwc, const char *s, size_t n,
+		  mbstate_t *state)
+{
+  return __db_mbtowc (r, pwc, s, n, 54936, state);
+}
+
 extern "C" int
 __kr_mbtowc (struct _reent *r, wchar_t *pwc, const char *s, size_t n,
 	     mbstate_t *state)
diff --git a/winsup/doc/new-features.xml b/winsup/doc/new-features.xml
index 0858b01e5..a958f1600 100644
--- a/winsup/doc/new-features.xml
+++ b/winsup/doc/new-features.xml
@@ -41,6 +41,10 @@ files and uses the info for printing locale info like any other process
 could do.
 </para></listitem>
 
+<listitem><para>
+Add support for GB18030 codeset.
+</para></listitem>
+
 </itemizedlist>
 
 </sect2>