diff --git a/iconv/Makefile b/iconv/Makefile
index 07d77c9eca..9993f2d3f3 100644
--- a/iconv/Makefile
+++ b/iconv/Makefile
@@ -43,8 +43,19 @@ CFLAGS-charmap.c += -DCHARMAP_PATH='"$(i18ndir)/charmaps"' \
 CFLAGS-linereader.c += -DNO_TRANSLITERATION
 CFLAGS-simple-hash.c += -I../locale
 
-tests	= tst-iconv1 tst-iconv2 tst-iconv3 tst-iconv4 tst-iconv5 tst-iconv6 \
-	  tst-iconv7 tst-iconv8 tst-iconv-mt tst-iconv-opt
+tests = \
+	tst-iconv1 \
+	tst-iconv2 \
+	tst-iconv3 \
+	tst-iconv4 \
+	tst-iconv5 \
+	tst-iconv6 \
+	tst-iconv7 \
+	tst-iconv8 \
+	tst-iconv9 \
+	tst-iconv-mt \
+	tst-iconv-opt \
+	# tests
 
 others		= iconv_prog iconvconfig
 install-others-programs	= $(inst_bindir)/iconv
@@ -83,10 +94,15 @@ endif
 include ../Rules
 
 ifeq ($(run-built-tests),yes)
-LOCALES := en_US.UTF-8
+# We have to generate locales (list sorted alphabetically)
+LOCALES := \
+	C.UTF-8 \
+	en_US.UTF-8 \
+	# LOCALES
 include ../gen-locales.mk
 
 $(objpfx)tst-iconv-opt.out: $(gen-locales)
+$(objpfx)tst-iconv9.out: $(gen-locales)
 endif
 
 $(inst_bindir)/iconv: $(objpfx)iconv_prog $(+force)
diff --git a/iconv/tst-iconv9.c b/iconv/tst-iconv9.c
new file mode 100644
index 0000000000..78a5324279
--- /dev/null
+++ b/iconv/tst-iconv9.c
@@ -0,0 +1,87 @@
+/* Verify that using C.UTF-8 works.
+
+   Copyright (C) 2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <iconv.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <string.h>
+#include <support/support.h>
+#include <support/check.h>
+
+/* This test does two things:
+   (1) Verify that we have likely included translit_combining in C.UTF-8.
+   (2) Verify default_missing is '?' as expected.  */
+
+/* ISO-8859-1 encoding of "für".  */
+char iso88591_in[] = { 0x66, 0xfc, 0x72, 0x0 };
+/* ASCII transliteration is "fur" with C.UTF-8 translit_combining.  */
+char ascii_exp[] = { 0x66, 0x75, 0x72, 0x0 };
+
+/* First 3-byte UTF-8 code point.  */
+char utf8_in[] = { 0xe0, 0xa0, 0x80, 0x0 };
+/* There is no ASCII transliteration for SAMARITAN LETTER ALAF
+   so we get default_missing used which is '?'.  */
+char default_missing_exp[] = { 0x3f, 0x0 };
+
+static int
+do_test (void)
+{
+  char ascii_out[5];
+  iconv_t cd;
+  char *inbuf;
+  char *outbuf;
+  size_t inbytes;
+  size_t outbytes;
+  size_t n;
+
+  /* The C.UTF-8 locale should include translit_combining, which provides
+     the transliteration for "LATIN SMALL LETTER U WITH DIAERESIS" which
+     is not provided by locale/C-translit.h.in.  */
+  xsetlocale (LC_ALL, "C.UTF-8");
+
+  /* From ISO-8859-1 to ASCII. */
+  cd = iconv_open ("ASCII//TRANSLIT,IGNORE", "ISO-8859-1");
+  TEST_VERIFY (cd != (iconv_t) -1);
+  inbuf = iso88591_in;
+  inbytes = 3;
+  outbuf = ascii_out;
+  outbytes = 3;
+  n = iconv (cd, &inbuf, &inbytes, &outbuf, &outbytes);
+  TEST_VERIFY (n != -1);
+  *outbuf = '\0';
+  TEST_COMPARE_BLOB (ascii_out, 3, ascii_exp, 3);
+  TEST_VERIFY (iconv_close (cd) == 0);
+
+  /* From UTF-8 to ASCII. */
+  cd = iconv_open ("ASCII//TRANSLIT,IGNORE", "UTF-8");
+  TEST_VERIFY (cd != (iconv_t) -1);
+  inbuf = utf8_in;
+  inbytes = 3;
+  outbuf = ascii_out;
+  outbytes = 3;
+  n = iconv (cd, &inbuf, &inbytes, &outbuf, &outbytes);
+  TEST_VERIFY (n != -1);
+  *outbuf = '\0';
+  TEST_COMPARE_BLOB (ascii_out, 1, default_missing_exp, 1);
+  TEST_VERIFY (iconv_close (cd) == 0);
+
+  return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/localedata/C.UTF-8.in b/localedata/C.UTF-8.in
new file mode 100644
index 0000000000..c31dcc2aa0
--- /dev/null
+++ b/localedata/C.UTF-8.in
@@ -0,0 +1,157 @@
+ ; <U1>
+ ; <U2>
+ ; <U3>
+ ; <U4>
+ ; <U5>
+ ; <U6>
+ ; <U7>
+ ; <U8>
+ ; <UE>
+ ; <UF>
+ ; <U10>
+ ; <U11>
+ ; <U12>
+ ; <U13>
+ ; <U14>
+ ; <U15>
+ ; <U16>
+ ; <U17>
+ ; <U18>
+ ; <U19>
+ ; <U1A>
+ ; <U1B>
+ ; <U1C>
+ ; <U1D>
+ ; <U1E>
+ ; <U1F>
+! ; <U21>
+" ; <U22>
+# ; <U23>
+$ ; <U24>
+% ; <U25>
+& ; <U26>
+' ; <U27>
+) ; <U29>
+* ; <U2A>
++ ; <U2B>
+, ; <U2C>
+- ; <U2D>
+. ; <U2E>
+/ ; <U2F>
+0 ; <U30>
+1 ; <U31>
+2 ; <U32>
+3 ; <U33>
+4 ; <U34>
+5 ; <U35>
+6 ; <U36>
+7 ; <U37>
+8 ; <U38>
+9 ; <U39>
+< ; <U3C>
+= ; <U3D>
+> ; <U3E>
+? ; <U3F>
+@ ; <U40>
+A ; <U41>
+B ; <U42>
+C ; <U43>
+D ; <U44>
+E ; <U45>
+F ; <U46>
+G ; <U47>
+H ; <U48>
+I ; <U49>
+J ; <U4A>
+K ; <U4B>
+L ; <U4C>
+M ; <U4D>
+N ; <U4E>
+O ; <U4F>
+P ; <U50>
+Q ; <U51>
+R ; <U52>
+S ; <U53>
+T ; <U54>
+U ; <U55>
+V ; <U56>
+W ; <U57>
+X ; <U58>
+Y ; <U59>
+Z ; <U5A>
+[ ; <U5B>
+\ ; <U5C>
+] ; <U5D>
+^ ; <U5E>
+_ ; <U5F>
+` ; <U60>
+a ; <U61>
+b ; <U62>
+c ; <U63>
+d ; <U64>
+e ; <U65>
+f ; <U66>
+g ; <U67>
+h ; <U68>
+i ; <U69>
+j ; <U6A>
+k ; <U6B>
+l ; <U6C>
+m ; <U6D>
+n ; <U6E>
+o ; <U6F>
+p ; <U70>
+q ; <U71>
+r ; <U72>
+s ; <U73>
+t ; <U74>
+u ; <U75>
+v ; <U76>
+w ; <U77>
+x ; <U78>
+y ; <U79>
+z ; <U7A>
+{ ; <U7B>
+| ; <U7C>
+} ; <U7D>
+~ ; <U7E>
+ ; <U7F>
+ ; <U80>
+ÿ ; <UFF>
+Ā ; <U100>
+࿿ ; <UFFF>
+က ; <U1000>
+� ; <UFFFD>
+ ; <UFFFF>
+𐀀 ; <U10000>
+🿿 ; <U1FFFF>
+𠀀 ; <U20000>
+𯿿 ; <U2FFFF>
+𰀀 ; <U30000>
+𿿾 ; <U3FFFE>
+񀀀 ; <U40000>
+񏿿 ; <U4FFFF>
+񐀀 ; <U50000>
+񟿿 ; <U5FFFF>
+񠀀 ; <U60000>
+񯿿 ; <U6FFFF>
+񰀀 ; <U70000>
+񿿿 ; <U7FFFF>
+򀀀 ; <U80000>
+򏿿 ; <U8FFFF>
+򐀀 ; <U90000>
+򟿿 ; <U9FFFF>
+򠀀 ; <UA0000>
+򯿿 ; <UAFFFF>
+򰀀 ; <UB0000>
+򿿿 ; <UBFFFF>
+󀀁 ; <UC0001>
+󏿌 ; <UCFFCC>
+󐀎 ; <UD000E>
+󟿿 ; <UDFFFF>
+󠀁 ; <UE0001>
+󯿿 ; <UEFFFF>
+󰀁 ; <UF0001>
+󿿿 ; <UFFFFF>
+􀀁 ; <U100001>
+􏿿 ; <U10FFFF>
diff --git a/localedata/Makefile b/localedata/Makefile
index f585e0dd41..66a269641b 100644
--- a/localedata/Makefile
+++ b/localedata/Makefile
@@ -47,6 +47,7 @@ test-input := \
 	bg_BG.UTF-8 \
 	br_FR.UTF-8 \
 	bs_BA.UTF-8 \
+	C.UTF-8 \
 	ckb_IQ.UTF-8 \
 	cmn_TW.UTF-8 \
 	crh_UA.UTF-8 \
@@ -206,6 +207,7 @@ LOCALES := \
 	bg_BG.UTF-8 \
 	br_FR.UTF-8 \
 	bs_BA.UTF-8 \
+	C.UTF-8 \
 	ckb_IQ.UTF-8 \
 	cmn_TW.UTF-8 \
 	crh_UA.UTF-8 \
diff --git a/localedata/SUPPORTED b/localedata/SUPPORTED
index 1ee5b5e8c8..d768aa4795 100644
--- a/localedata/SUPPORTED
+++ b/localedata/SUPPORTED
@@ -79,6 +79,7 @@ brx_IN/UTF-8 \
 bs_BA.UTF-8/UTF-8 \
 bs_BA/ISO-8859-2 \
 byn_ER/UTF-8 \
+C.UTF-8/UTF-8 \
 ca_AD.UTF-8/UTF-8 \
 ca_AD/ISO-8859-15 \
 ca_ES.UTF-8/UTF-8 \
diff --git a/localedata/locales/C b/localedata/locales/C
new file mode 100644
index 0000000000..651691c724
--- /dev/null
+++ b/localedata/locales/C
@@ -0,0 +1,194 @@
+escape_char /
+comment_char %
+% Locale for C locale in UTF-8
+
+LC_IDENTIFICATION
+title      "C locale"
+source     ""
+address    ""
+contact    ""
+email      "bug-glibc-locales@gnu.org"
+tel        ""
+fax        ""
+language   ""
+territory  ""
+revision   "2.0"
+date       "2020-06-28"
+category  "i18n:2012";LC_IDENTIFICATION
+category  "i18n:2012";LC_CTYPE
+category  "i18n:2012";LC_COLLATE
+category  "i18n:2012";LC_TIME
+category  "i18n:2012";LC_NUMERIC
+category  "i18n:2012";LC_MONETARY
+category  "i18n:2012";LC_MESSAGES
+category  "i18n:2012";LC_PAPER
+category  "i18n:2012";LC_NAME
+category  "i18n:2012";LC_ADDRESS
+category  "i18n:2012";LC_TELEPHONE
+category  "i18n:2012";LC_MEASUREMENT
+END LC_IDENTIFICATION
+
+LC_CTYPE
+% Include only the i18n character type classes without any of the
+% transliteration that i18n uses by default.
+copy "i18n_ctype"
+
+% Include the neutral transliterations.  The builtin C and
+% POSIX locales have +1600 transliterations that are built into
+% the locales, and these are a superset of those.
+translit_start
+include "translit_neutral";""
+% We must use '?' for default_missing because the transliteration
+% framework includes it directly into the output and so it must
+% be compatible with ASCII if that is the target character set.
+default_missing <U003F>
+translit_end
+
+% Include the transliterations that can convert combined cahracters.
+% These are generally expected by users.
+translit_start
+include "translit_combining";""
+translit_end
+
+END LC_CTYPE
+
+LC_COLLATE
+% The keyword 'strcmp_collation' in any part of any LC_COLLATE
+% immediately discards all collation information and causes the
+% locale to use strcmp for collation comparison.  This is exactly
+% what is needed for C (ASCII) or C.UTF-8.
+strcmp_collation
+END LC_COLLATE
+
+LC_MONETARY
+
+% This is the 14652 i18n fdcc-set definition for the LC_MONETARY
+% category (except for the int_curr_symbol and currency_symbol, they are
+% empty in the 14652 i18n fdcc-set definition and also empty in
+% glibc/locale/C-monetary.c.).
+int_curr_symbol     ""
+currency_symbol     ""
+mon_decimal_point   "."
+mon_thousands_sep   ""
+mon_grouping        -1
+positive_sign       ""
+negative_sign       "-"
+int_frac_digits     -1
+frac_digits         -1
+p_cs_precedes       -1
+int_p_sep_by_space  -1
+p_sep_by_space      -1
+n_cs_precedes       -1
+int_n_sep_by_space  -1
+n_sep_by_space      -1
+p_sign_posn         -1
+n_sign_posn         -1
+%
+END LC_MONETARY
+
+LC_NUMERIC
+% This is the POSIX Locale definition for
+% the LC_NUMERIC category.
+%
+decimal_point   "."
+thousands_sep   ""
+grouping        -1
+END LC_NUMERIC
+
+LC_TIME
+% This is the POSIX Locale definition for the LC_TIME category with the
+% exception that time is per ISO 8601 and 24-hour.
+%
+% Abbreviated weekday names (%a)
+abday       "Sun";"Mon";"Tue";"Wed";"Thu";"Fri";"Sat"
+
+% Full weekday names (%A)
+day         "Sunday";"Monday";"Tuesday";"Wednesday";"Thursday";/
+            "Friday";"Saturday"
+
+% Abbreviated month names (%b)
+abmon       "Jan";"Feb";"Mar";"Apr";"May";"Jun";"Jul";"Aug";"Sep";/
+            "Oct";"Nov";"Dec"
+
+% Full month names (%B)
+mon         "January";"February";"March";"April";"May";"June";"July";/
+            "August";"September";"October";"November";"December"
+
+% Week description, consists of three fields:
+% 1. Number of days in a week.
+% 2. Gregorian date that is a first weekday (19971130 for Sunday, 19971201 for Monday).
+% 3. The weekday number to be contained in the first week of the year.
+%
+% ISO 8601 conforming applications should use the values 7, 19971201 (a
+% Monday), and 4 (Thursday), respectively.
+week    7;19971201;4
+first_weekday	1
+first_workday	2
+
+% Appropriate date and time representation (%c)
+d_t_fmt "%a %b %e %H:%M:%S %Y"
+
+% Appropriate date representation (%x)
+d_fmt   "%m/%d/%y"
+
+% Appropriate time representation (%X)
+t_fmt   "%H:%M:%S"
+
+% Appropriate AM/PM time representation (%r)
+t_fmt_ampm "%I:%M:%S %p"
+
+% Equivalent of AM/PM (%p)
+am_pm	"AM";"PM"
+
+% Appropriate date representation (date(1))   "%a %b %e %H:%M:%S %Z %Y"
+date_fmt	"%a %b %e %H:%M:%S %Z %Y"
+END LC_TIME
+
+LC_MESSAGES
+% This is the POSIX Locale definition for
+% the LC_NUMERIC category.
+%
+yesexpr "^[yY]"
+noexpr  "^[nN]"
+yesstr  "Yes"
+nostr   "No"
+END LC_MESSAGES
+
+LC_PAPER
+% This is the ISO/IEC 14652 "i18n" definition for
+% the LC_PAPER category.
+% (A4 paper, this is also used in the built in C/POSIX
+% locale in glibc/locale/C-paper.c)
+height   297
+width    210
+END LC_PAPER
+
+LC_NAME
+% This is the ISO/IEC 14652 "i18n" definition for
+% the LC_NAME category.
+% (also used in the built in C/POSIX locale in glibc/locale/C-name.c)
+name_fmt    "%p%t%g%t%m%t%f"
+END LC_NAME
+
+LC_ADDRESS
+% This is the ISO/IEC 14652 "i18n" definition for
+% the LC_ADDRESS category.
+% (also used in the built in C/POSIX locale in glibc/locale/C-address.c)
+postal_fmt    "%a%N%f%N%d%N%b%N%s %h %e %r%N%C-%z %T%N%c%N"
+END LC_ADDRESS
+
+LC_TELEPHONE
+% This is the ISO/IEC 14652 "i18n" definition for
+% the LC_TELEPHONE category.
+% "+%c %a %l"
+tel_int_fmt    "+%c %a %l"
+% (also used in the built in C/POSIX locale in glibc/locale/C-telephone.c)
+END LC_TELEPHONE
+
+LC_MEASUREMENT
+% This is the ISO/IEC 14652 "i18n" definition for
+% the LC_MEASUREMENT category.
+% (same as in the built in C/POSIX locale in glibc/locale/C-measurement.c)
+%metric
+measurement    1
+END LC_MEASUREMENT
