diff --git a/changelog/updates/2022-01-01-timezone-data-2021a-update.md b/changelog/updates/2022-01-01-timezone-data-2021a-update.md
new file mode 100644
index 00000000000..1876cf88717
--- /dev/null
+++ b/changelog/updates/2022-01-01-timezone-data-2021a-update.md
@@ -0,0 +1 @@
+- timezone-data ([2021a](https://mm.icann.org/pipermail/tz-announce/2021-January/000065.html))
diff --git a/sys-libs/timezone-data/Manifest b/sys-libs/timezone-data/Manifest
index d555b63529a..95722eb438f 100644
--- a/sys-libs/timezone-data/Manifest
+++ b/sys-libs/timezone-data/Manifest
@@ -1,4 +1,2 @@
-DIST tzcode2019b.tar.gz 251196 BLAKE2B 73ed8d44675a25e0497b77cc20ca3cc5b137297e48ce679cb6e8d809f4f25d73631064e0f1c2d917b986baa10bad9369bac42d583573519e7f3a94c864b18886 SHA512 bcfb417fe3b7c39e702da0090291db0489744f733010ae183007fce5e441bfce885fb25ed11730cf7f363572e107d7ff0c4b38691bb99def2d8cf7017c05720f
-DIST tzcode2019c.tar.gz 253560 BLAKE2B 62552e7e78ebb50c111f9a99119843fe9b5dad9e1abb5ba0f1cf0a931cf00fc49684a6b378f5ea4cb31aca8af5b0c3b697b87048ef36a445536ec2fc5b943440 SHA512 61ef36385f501c338c263081486de0d1fccd454b86f8777b0dbad4ea3f21bbde059d0a91c23e207b167ed013127d3db8b7528f0188814a8b44d1f946b19d9b8b
-DIST tzdata2019b.tar.gz 384667 BLAKE2B c045d137cbb09e1109916dfdb1265ceb560d589ded9b05aa0cfe75f5fcb19057ded4d4f12f47c895020ed02bc4138de995eadac497eb3663579b094164d7e3ad SHA512 c0104078d994e501d80a41bea31364b1390a75c2fbf42968a8343a090e2ac2eddbc58770ca470b192ea19dec89fcc634141a1de703ea2ffa0325176a64afe1fc
-DIST tzdata2019c.tar.gz 392087 BLAKE2B d7a21e57391d321b5c84e1ba2286ff0dd154c435d40015d999c8c6f2f1bea3c13d832c0752af313c9aa4dafe6a261e1e92bfd79523448fcd585188a53454e31a SHA512 2921cbb2fd44a6b8f7f2ed42c13fbae28195aa5c2eeefa70396bc97cdbaad679c6cc3c143da82cca5b0279065c02389e9af536904288c12886bf345baa8c6565
+DIST tzcode2021a.tar.gz 262204 BLAKE2B 4072685f2344602ffcfe32a7bf92d3b0d93e38ffca842f1c07a60db5e26f1f18ab32fc7b5f155b0bdab49f8d0bfcd5b58f4a192b4d06d7d9639893e5cb596328 SHA512 bf1d53bcbfecd3b09d57a9e6d3cb49b5dc5f8e1b6674b67e7f974e1a268c2aaf13ca89a7ef12f49d0665aff782bd72685e00c22a41ca88a028da0429f972fd45
+DIST tzdata2021a.tar.gz 411892 BLAKE2B b8d177e90e22bd8a3fd23c9a9c19896cb245efd8e768b59ab8c63e56ab141e67331f3231e3a7c802f844375049cfd902e14e912ce677b3aea38fc0d968905e87 SHA512 7cdd762ec90ce12a30fa36b1d66d1ea82d9fa21e514e2b9c7fcbe2541514ee0fadf30843ff352c65512fb270857b51d1517b45e1232b89c6f954ba9ff1833bb3
diff --git a/sys-libs/timezone-data/metadata.xml b/sys-libs/timezone-data/metadata.xml
index a74a2f3c906..0e4c5ee4f0a 100644
--- a/sys-libs/timezone-data/metadata.xml
+++ b/sys-libs/timezone-data/metadata.xml
@@ -1,10 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<!DOCTYPE pkgmetadata SYSTEM "http://www.gentoo.org/dtd/metadata.dtd">
+<!DOCTYPE pkgmetadata SYSTEM "https://www.gentoo.org/dtd/metadata.dtd">
 <pkgmetadata>
-  <maintainer type="person">
-    <email>djc@gentoo.org</email>
-    <name>Dirkjan Ochtman</name>
-  </maintainer>
   <maintainer type="project">
     <email>toolchain@gentoo.org</email>
     <name>Gentoo Toolchain Project</name>
@@ -15,5 +11,9 @@
       when counting seconds since the epoch (while POSIX does not) as they are
       based on the TAI (International Atomic Time) clock
     </flag>
+    <flag name="zic-slim">
+      Default to 'slim' file format for /usr/share/zoneinfo. Otherwise 'fat' format
+      is used. Not all programs can handle 'slim' format'.
+    </flag>
   </use>
 </pkgmetadata>
diff --git a/sys-libs/timezone-data/timezone-data-2019b-r2.ebuild b/sys-libs/timezone-data/timezone-data-2019b-r2.ebuild
deleted file mode 100644
index 7b0606faa54..00000000000
--- a/sys-libs/timezone-data/timezone-data-2019b-r2.ebuild
+++ /dev/null
@@ -1,178 +0,0 @@
-# Copyright 1999-2019 Gentoo Authors
-# Distributed under the terms of the GNU General Public License v2
-
-EAPI="7"
-
-inherit toolchain-funcs flag-o-matic
-
-code_ver=${PV}
-data_ver=${PV}
-DESCRIPTION="Timezone data (/usr/share/zoneinfo) and utilities (tzselect/zic/zdump)"
-HOMEPAGE="https://www.iana.org/time-zones"
-SRC_URI="https://www.iana.org/time-zones/repository/releases/tzdata${data_ver}.tar.gz
-	https://www.iana.org/time-zones/repository/releases/tzcode${code_ver}.tar.gz"
-
-LICENSE="BSD public-domain"
-SLOT="0"
-KEYWORDS="alpha amd64 arm arm64 hppa ia64 m68k ~mips ppc ppc64 ~riscv s390 sh sparc x86 ~amd64-linux ~x86-linux ~ppc-macos ~x64-macos ~x86-macos ~x64-solaris"
-IUSE="nls leaps-timezone"
-
-DEPEND="nls? ( virtual/libintl )"
-RDEPEND="${DEPEND}
-	!sys-libs/glibc[vanilla(+)]"
-
-S=${WORKDIR}
-
-src_prepare() {
-	default
-
-	# check_web contacts validator.w3.org
-	sed -i -e 's/check_tables check_web/check_tables/g' \
-		Makefile || die "Failed to disable check_web"
-
-	tc-is-cross-compiler && cp -pR "${S}" "${S}"-native
-}
-
-src_configure() {
-	tc-export CC
-
-	append-lfs-flags #471102
-
-	if use elibc_Darwin ; then
-		append-cppflags -DSTD_INSPIRED #138251
-	fi
-
-	append-cppflags -DHAVE_GETTEXT=$(usex nls 1 0) -DTZ_DOMAIN='\"libc\"'
-	LDLIBS=""
-	if use nls ; then
-		# See if an external libintl is available. #154181 #578424
-		local c="${T}/test"
-		echo 'main(){}' > "${c}.c"
-		if $(tc-getCC) ${CPPFLAGS} ${CFLAGS} ${LDFLAGS} "${c}.c" -o "${c}" -lintl 2>/dev/null ; then
-			LDLIBS+=" -lintl"
-		fi
-	fi
-}
-
-_emake() {
-	emake \
-		REDO=$(usex leaps-timezone posix_right posix_only) \
-		TZDATA_TEXT= \
-		TOPDIR="${EPREFIX}" \
-		ZICDIR='$(TOPDIR)/usr/bin' \
-		"$@"
-}
-
-src_compile() {
-	_emake \
-		AR="$(tc-getAR)" \
-		cc="$(tc-getCC)" \
-		RANLIB="$(tc-getRANLIB)" \
-		CFLAGS="${CFLAGS} -std=gnu99 ${CPPFLAGS}" \
-		LDFLAGS="${LDFLAGS}" \
-		LDLIBS="${LDLIBS}"
-	if tc-is-cross-compiler ; then
-		_emake -C "${S}"-native \
-			AR="$(tc-getBUILD_AR)" \
-			cc="$(tc-getBUILD_CC)" \
-			RANLIB="$(tc-getBUILD_RANLIB)" \
-			CFLAGS="${BUILD_CFLAGS} ${BUILD_CPPFLAGS}" \
-			LDFLAGS="${BUILD_LDFLAGS}" \
-			LDLIBS="${LDLIBS}" \
-			zic
-	fi
-}
-
-src_test() {
-	# VALIDATE_ENV is used for extended/web based tests.  Punt on them.
-	emake check VALIDATE_ENV=true
-}
-
-src_install() {
-	local zic=""
-	tc-is-cross-compiler && zic="zic=${S}-native/zic"
-	_emake install ${zic} DESTDIR="${D}" LIBDIR="/nukeit"
-	rm -rf "${D}/nukeit" "${ED}/etc" || die
-
-	insinto /usr/share/zoneinfo
-	doins "${S}"/leap-seconds.list
-
-	# Delete man pages installed by man-pages package.
-	rm "${ED}"/usr/share/man/man5/tzfile.5* "${ED}"/usr/share/man/man8/{tzselect,zdump,zic}.8 || die
-	dodoc CONTRIBUTING README NEWS *.html
-}
-
-get_TIMEZONE() {
-	local tz src="${EROOT}/etc/timezone"
-	if [[ -e ${src} ]] ; then
-		tz=$(sed -e 's:#.*::' -e 's:[[:space:]]*::g' -e '/^$/d' "${src}")
-	else
-		tz="FOOKABLOIE"
-	fi
-	[[ -z ${tz} ]] && return 1 || echo "${tz}"
-}
-
-pkg_preinst() {
-	local tz=$(get_TIMEZONE)
-	if [[ ${tz} == right/* || ${tz} == posix/* ]] ; then
-		eerror "The right & posix subdirs are no longer installed as subdirs -- they have been"
-		eerror "relocated to match upstream paths as sibling paths.  Further, posix/xxx is the"
-		eerror "same as xxx, so you should simply drop the posix/ prefix.  You also should not"
-		eerror "be using right/xxx for the system timezone as it breaks programs."
-		die "Please fix your timezone setting"
-	fi
-
-	# Trim the symlink by hand to avoid portage's automatic protection checks.
-	rm -f "${EROOT}"/usr/share/zoneinfo/posix
-
-	if has_version "<=${CATEGORY}/${PN}-2015c" ; then
-		elog "Support for accessing posix/ and right/ directly has been dropped to match"
-		elog "upstream.  There is no need to set TZ=posix/xxx as it is the same as TZ=xxx."
-		elog "For TZ=right/, you can use TZ=../zoneinfo-leaps/xxx instead.  See this post"
-		elog "for details: https://mm.icann.org/pipermail/tz/2015-February/022024.html"
-	fi
-}
-
-configure_tz_data() {
-	# make sure the /etc/localtime file does not get stale #127899
-	local tz src="${EROOT}/etc/timezone" etc_lt="${EROOT}/etc/localtime"
-
-	# If it's a symlink, assume the user knows what they're doing and
-	# they're managing it themselves. #511474
-	if [[ -L "${etc_lt}" ]] ; then
-		einfo "Assuming your ${etc_lt} symlink is what you want; skipping update."
-		return 0
-	fi
-
-	if ! tz=$(get_TIMEZONE) ; then
-		einfo "Assuming your empty ${etc_lt} file is what you want; skipping update."
-		return 0
-	fi
-	if [[ "${tz}" == "FOOKABLOIE" ]] ; then
-		elog "You do not have TIMEZONE set in ${src}."
-
-		if [[ ! -e "${etc_lt}" ]] ; then
-			cp -f "${EROOT}"/usr/share/zoneinfo/Factory "${etc_lt}"
-			elog "Setting ${etc_lt} to Factory."
-		else
-			elog "Skipping auto-update of ${etc_lt}."
-		fi
-		return 0
-	fi
-
-	if [[ ! -e "${EROOT}/usr/share/zoneinfo/${tz}" ]] ; then
-		elog "You have an invalid TIMEZONE setting in ${src}"
-		elog "Your ${etc_lt} has been reset to Factory; enjoy!"
-		tz="Factory"
-	fi
-	einfo "Updating ${etc_lt} with ${EROOT}/usr/share/zoneinfo/${tz}"
-	cp -f "${EROOT}/usr/share/zoneinfo/${tz}" "${etc_lt}"
-}
-
-pkg_config() {
-	configure_tz_data
-}
-
-pkg_postinst() {
-	configure_tz_data
-}
diff --git a/sys-libs/timezone-data/timezone-data-2019c.ebuild b/sys-libs/timezone-data/timezone-data-2021a-r1.ebuild
similarity index 82%
rename from sys-libs/timezone-data/timezone-data-2019c.ebuild
rename to sys-libs/timezone-data/timezone-data-2021a-r1.ebuild
index 736b9888a13..2d30e145a42 100644
--- a/sys-libs/timezone-data/timezone-data-2019c.ebuild
+++ b/sys-libs/timezone-data/timezone-data-2021a-r1.ebuild
@@ -1,4 +1,4 @@
-# Copyright 1999-2019 Gentoo Authors
+# Copyright 1999-2022 Gentoo Authors
 # Distributed under the terms of the GNU General Public License v2
 
 EAPI="7"
@@ -14,14 +14,17 @@ SRC_URI="https://www.iana.org/time-zones/repository/releases/tzdata${data_ver}.t
 
 LICENSE="BSD public-domain"
 SLOT="0"
-KEYWORDS="alpha amd64 arm arm64 hppa ia64 m68k ~mips ppc ppc64 ~riscv s390 sh sparc x86 ~amd64-linux ~x86-linux ~ppc-macos ~x64-macos ~x86-macos ~x64-solaris"
-IUSE="nls leaps-timezone"
+KEYWORDS="~alpha amd64 arm arm64 hppa ~ia64 ~m68k ~mips ppc ppc64 ~riscv ~s390 sparc x86 ~x64-cygwin ~amd64-linux ~x86-linux ~ppc-macos ~x64-macos ~sparc-solaris ~sparc64-solaris ~x64-solaris ~x86-solaris"
+IUSE="nls leaps-timezone zic-slim"
 
 DEPEND="nls? ( virtual/libintl )"
 RDEPEND="${DEPEND}
 	!sys-libs/glibc[vanilla(+)]"
 
-S=${WORKDIR}
+src_unpack() {
+	mkdir -p "${S}" && cd "${S}" || die
+	default
+}
 
 src_prepare() {
 	default
@@ -43,6 +46,11 @@ src_configure() {
 	fi
 
 	append-cppflags -DHAVE_GETTEXT=$(usex nls 1 0) -DTZ_DOMAIN='\"libc\"'
+
+	# Upstream default is 'slim', but it breaks quite a few programs
+	# that parse /etc/localtime directly: bug# 747538.
+	append-cppflags -DZIC_BLOAT_DEFAULT='\"'$(usex zic-slim slim fat)'\"'
+
 	LDLIBS=""
 	if use nls ; then
 		# See if an external libintl is available. #154181 #578424
@@ -57,7 +65,6 @@ src_configure() {
 _emake() {
 	emake \
 		REDO=$(usex leaps-timezone posix_right posix_only) \
-		TZDATA_TEXT= \
 		TOPDIR="${EPREFIX}" \
 		ZICDIR='$(TOPDIR)/usr/bin' \
 		"$@"