diff --git a/dev-ml/llvm/Manifest b/dev-ml/llvm/Manifest
index aaf62b13972cd..c236d706a884c 100644
--- a/dev-ml/llvm/Manifest
+++ b/dev-ml/llvm/Manifest
@@ -12,4 +12,6 @@ DIST llvm-project-20.1.7.src.tar.xz 147245448 BLAKE2B f7c57d1eba4e97e875b624dec3
 DIST llvm-project-20.1.7.src.tar.xz.sig 566 BLAKE2B 72ce2a18c211cfce9581a9e3e71f1c55cf18672aa355267581220e1a89e3327f9e16107970b69bb8f10f390baa5e286487bdc4cc0a7d9155ec13a4977cd3f472 SHA512 eff885059d547f57b98bda1fc9631f716ca6c650cd48203d9ed5443a6afb9a2d4d91d3f5c8618e307c0a44b3040bce61fdc6bce965073adc537655755d9f2112
 DIST llvm-project-20.1.8.src.tar.xz 147242952 BLAKE2B 7657ac0b26acc5affb1bfc91b912ade3191c5d77f3979d5a80d5f6ce52f56a7d1c448bd257398390bf10838f02faa6f3ece37a7327cced69d165ec2e2e699316 SHA512 f330e72e6a1da468569049437cc0ba7a41abb816ccece7367189344f7ebfef730f4788ac7af2bef0aa8a49341c15ab1d31e941ffa782f264d11fe0dc05470773
 DIST llvm-project-20.1.8.src.tar.xz.sig 566 BLAKE2B 85beedfcff1195a974fab2c667b9efd4b715b3480c1b44b1b887fe32c69f72aca0d3b8fb276c03b6cc5a866622f669047aeee5ccb976640b4008ccd31dce77a4 SHA512 d74369bdb4d1b82775161ea53c9c5f3a23ce810f4df5ff617123023f9d8ce720e7d6ecc9e17f8ebd39fd9e7a9de79560abdf2ffe73bcb907a43148d43665d619
+DIST llvm-project-21.1.0-rc1.src.tar.xz 158955624 BLAKE2B 6a33d48f41f92cd8731011678afdf4c6f6a4581af04483626c511d1c9410d62788eb660e05cdfe418085509b576c29eec5bb07ae7ddc993e9931287657c11e03 SHA512 7ab3d1bb49bd3c5c9c1490cd865fdef027c25d64bb7f6a2a16c11c311670d08b7a214323ae4781aa0f49973deb0039ebea9d04887089df8dedf65080acdfc871
+DIST llvm-project-21.1.0-rc1.src.tar.xz.sig 438 BLAKE2B d3736b7f4bb6133e542fb3f52d1b76acc2920558e61bbbeeec6e5b7639ca54e229803b27baa4aedd2134c11fb4439064ac36e90c8c1831a503dd1754efee8da6 SHA512 6b9565f270fae4e534a160916bbd01ccd0e1295bf17df13f3be05bed4f058c0e935ba7385aba74a195d3a13868d81f2a0cf4be966b216fc6d7b56002f33eb4a0
 DIST llvm-project-b6313b381ac0e83012ea11b4549cd8cb39b686d2.tar.gz 242588863 BLAKE2B 81e7db20b849ce7a5c7c6b03d1e62a2e225eb68473509baf0adc9e74a2f759d251b61b018528d5db93f77b65ac355a71ede81bec7e97f9c71a41f34a5d8625bd SHA512 258b99ef79d7efd4ec58d6a5370969b8032149f05fea4dfa841398ed59a550219f4223cd79581bc6fc4428dd9b09f44abf9f5369348831f463b9eb401a614d61
diff --git a/dev-ml/llvm/llvm-21.1.0_rc1.ebuild b/dev-ml/llvm/llvm-21.1.0_rc1.ebuild
new file mode 100644
index 0000000000000..e28a14abee10a
--- /dev/null
+++ b/dev-ml/llvm/llvm-21.1.0_rc1.ebuild
@@ -0,0 +1,107 @@
+# Copyright 1999-2025 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+PYTHON_COMPAT=( python3_{11..14} )
+inherit cmake llvm.org llvm-utils python-any-r1
+
+DESCRIPTION="OCaml bindings for LLVM"
+HOMEPAGE="https://llvm.org/"
+
+LICENSE="Apache-2.0-with-LLVM-exceptions UoI-NCSA"
+SLOT="0/${PV}"
+IUSE="+debug test"
+RESTRICT="!test? ( test )"
+
+RDEPEND="
+	>=dev-lang/ocaml-4.00.0:0=
+	dev-ml/ocaml-ctypes:=
+	~llvm-core/llvm-${PV}:=[debug?]
+	!llvm-core/llvm[ocaml(-)]
+"
+
+DEPEND="
+	${RDEPEND}
+"
+BDEPEND="
+	${PYTHON_DEPS}
+	dev-lang/perl
+	dev-ml/findlib
+"
+
+LLVM_COMPONENTS=( llvm cmake third-party )
+LLVM_USE_TARGETS=llvm
+llvm.org_set_globals
+
+src_configure() {
+	llvm_prepend_path "${LLVM_MAJOR}"
+
+	local libdir=$(get_libdir)
+	local mycmakeargs=(
+		-DLLVM_LIBDIR_SUFFIX=${libdir#lib}
+
+		-DBUILD_SHARED_LIBS=OFF
+		-DLLVM_BUILD_LLVM_DYLIB=ON
+		-DLLVM_LINK_LLVM_DYLIB=ON
+		-DLLVM_OCAML_OUT_OF_TREE=ON
+
+		# cheap hack: LLVM combines both anyway, and the only difference
+		# is that the former list is explicitly verified at cmake time
+		-DLLVM_TARGETS_TO_BUILD=""
+		-DLLVM_EXPERIMENTAL_TARGETS_TO_BUILD="${LLVM_TARGETS// /;}"
+		-DLLVM_BUILD_TESTS=$(usex test)
+
+		# disable various irrelevant deps and settings
+		-DLLVM_ENABLE_FFI=OFF
+		-DLLVM_ENABLE_TERMINFO=OFF
+		-DHAVE_HISTEDIT_H=NO
+		-DLLVM_ENABLE_ASSERTIONS=$(usex debug)
+		-DLLVM_ENABLE_EH=ON
+		-DLLVM_ENABLE_RTTI=ON
+
+		-DLLVM_HOST_TRIPLE="${CHOST}"
+
+		-DPython3_EXECUTABLE="${PYTHON}"
+
+		# TODO: ocamldoc
+	)
+
+	use test && mycmakeargs+=(
+		-DLLVM_LIT_ARGS="$(get_lit_flags)"
+	)
+
+	# LLVM_ENABLE_ASSERTIONS=NO does not guarantee this for us, #614844
+	# also: custom rules for OCaml do not work for CPPFLAGS
+	use debug || local -x CFLAGS="${CFLAGS} -DNDEBUG"
+	cmake_src_configure
+
+	local llvm_libdir=$(llvm-config --libdir)
+	# an ugly hack; TODO: figure out a way to pass -L to ocaml...
+	cd "${BUILD_DIR}/${libdir}" || die
+	ln -s "${llvm_libdir}"/*.so . || die
+
+	if use test; then
+		local llvm_bindir=$(llvm-config --bindir)
+		# Force using system-installed tools.
+		sed -i -e "/llvm_tools_dir/s@\".*\"@\"${llvm_bindir}\"@" \
+			"${BUILD_DIR}"/test/lit.site.cfg.py || die
+	fi
+}
+
+src_compile() {
+	cmake_build ocaml_all
+}
+
+src_test() {
+	# respect TMPDIR!
+	local -x LIT_PRESERVES_TMP=1
+	cmake_build check-llvm-bindings-ocaml
+}
+
+src_install() {
+	DESTDIR="${D}" \
+	cmake -P "${BUILD_DIR}"/bindings/ocaml/cmake_install.cmake || die
+
+	dodoc bindings/ocaml/README.txt
+}
diff --git a/llvm-core/llvm/Manifest b/llvm-core/llvm/Manifest
index 8d30a7f5528c5..4a7ad7d8a7ea0 100644
--- a/llvm-core/llvm/Manifest
+++ b/llvm-core/llvm/Manifest
@@ -8,7 +8,7 @@ DIST llvm-gentoo-patchset-15.0.7-r7.tar.xz 26012 BLAKE2B a3b6059e18e1347b1da18ef
 DIST llvm-gentoo-patchset-16.0.6-r5.tar.xz 19728 BLAKE2B 36b605401893034b2b560d26cfb57512c81eddbc35b25d9c3d1fe051b8825c38cae1b8ed999faf8fef564ca5578402d3979bc56ba0a5514dc62594d893696f41 SHA512 20a36b69dfc2b4796ce33318a28529ebdc213945ee67a983e4218117d2ee2c93be1ecb38b0e8189249c5806a442cba708e0890e1b7bf6376edec4403bcc71425
 DIST llvm-gentoo-patchset-17.0.6-r3.tar.xz 4648 BLAKE2B c709162068e83575f71a2ac2243665f47a3d42cac078daa5762bbd339d8593e8c1c5c58e2e415ba6659fe2f3c3824bd098c9be579103362084079140c0386f76 SHA512 251a33f146fcbdbe51c9e1ad7b08c2cd7d062d0b136c833cda8a5155c86080c506d575e4288cde4ba8530ca7f230c2afa63621878a8df0f23076a93c924e7d65
 DIST llvm-gentoo-patchset-18.1.8-r6.tar.xz 24816 BLAKE2B a7e9e007b05205fa7adba032ba932eba1996dd7ed6cd4cfb460a731f0d2e5fda2174f46c2ee5554ca7f82297a4baddbabc7fdfbd530056471853df957c221f2f SHA512 e1666bba6678eff3ee3666818a656ba7b8f964acb8466bd220bfbf0cc2922820e84b9daaa84c3a8ed26f3160fddea63fbc13872b007eb6922eaee462c08aeaef
-DIST llvm-gentoo-patchset-21.1.0-rc1.tar.xz 12612 BLAKE2B e6c5b52bd46fbbe705b4bf08e1bbafe94cfbe2ea4abf269203634840b9cacacf7e8ebd7ec11362becc1572548218378cfe35b60ded2b9077e894dc1c9c365da6 SHA512 ce07d7adc0f9758f629360bce1ae0e58b86465605080e0f8074fdfaacdcd2375e8a56e1f76987847958ee3c8480ed762002ee0d6d32b1e348e5ea8395f6126c2
+DIST llvm-gentoo-patchset-21.1.0-rc1-r1.tar.xz 13524 BLAKE2B 38644d60ac12ad8c91e8caf9a1bcb1c29b1aa03e8064dad5305eac4f13e56709d6bff053746b2f74330fabd0c3700a303ed079c351ba4c83c26ede83213a5370 SHA512 9a152dd7c52f0b6c8d3a3189c12f95cac4e6597d093eafb521715289f7e3136d8e85443782f87149edf1ec4e3d3a31d5f7dddb80e031f0c6ef568b0dadddce28
 DIST llvm-project-15.0.7.src.tar.xz 110936452 BLAKE2B f3d277e2029157329e5be78b78af36b0826a1dfd9a337992499bf701e33149665bfc47d5e14978e38f342559629a559f8b2ce328705ba34fdf6830f5ae9721a5 SHA512 4836d3603f32e8e54434cbfa8ef33d9d473ac5dc20ebf9c67132653c73f4524931abd1084655eaee5f20bcfcb91bcc4bbc5c4a0b603ad0c9029c556e14dc4c52
 DIST llvm-project-15.0.7.src.tar.xz.sig 566 BLAKE2B 47dc8c82d86237b80c6d85f83a6c9a6e9e174cf8e7f367b071e0cd9481d7cd408e991337c5624e07f3f370f26387c814f212808575ed1c1b58404d3e3836b7df SHA512 fc6891b440dd1175eb8df3790590af8d36bc92301660f84744ae15123475aeb900a151e6a8e7998ded27ec4d86871903ad0b89cd61164943054c2e3bc8d8beb2
 DIST llvm-project-16.0.6.src.tar.xz 118013488 BLAKE2B 95192d39cbd2914e5609db365965f1c00bfea6c2d653b3996bd2acef8a2b37e37f6fc8a9d2b65711ad72657e0ef52c42f733053cf65051e7822f27396c30406d SHA512 89a67ebfbbc764cc456e8825ecfa90707741f8835b1b2adffae0b227ab1fe5ca9cce75b0efaffc9ca8431cae528dc54fd838867a56a2b645344d9e82d19ab1b7
diff --git a/llvm-core/llvm/llvm-21.1.0_rc1.ebuild b/llvm-core/llvm/llvm-21.1.0_rc1.ebuild
index d511918cad34a..d4b3630de6d01 100644
--- a/llvm-core/llvm/llvm-21.1.0_rc1.ebuild
+++ b/llvm-core/llvm/llvm-21.1.0_rc1.ebuild
@@ -65,7 +65,7 @@ PDEPEND="
 
 LLVM_COMPONENTS=( llvm cmake third-party )
 LLVM_MANPAGES=1
-LLVM_PATCHSET=${PV/_/-}
+LLVM_PATCHSET=${PV/_/-}-r1
 LLVM_USE_TARGETS=provide
 llvm.org_set_globals