diff --git a/lang/rust/Makefile b/lang/rust/Makefile
--- a/lang/rust/Makefile
+++ b/lang/rust/Makefile
@@ -50,17 +50,22 @@
 # ?= to allow users to still overwrite it in make.conf.
 TMPDIR?=	${WRKDIR}
 
-OPTIONS_DEFINE=		DOCS GDB SOURCES WASM
+OPTIONS_DEFINE=		DOCS GDB PORT_LLVM SOURCES WASM
 OPTIONS_DEFAULT=	SOURCES WASM
 OPTIONS_EXCLUDE_armv6=	DOCS
 
 GDB_DESC=	Install ports gdb (necessary for debugging rust programs)
+PORT_LLVM_DESC=	Build against devel/llvm${LLVM_VER} (experimental)
 SOURCES_DESC=	Install source files
 WASM_DESC=	Build the WebAssembly target (wasm32-unknown-unknown)
 
 DOCS_VARS=		_RUST_BUILD_DOCS=true
 DOCS_VARS_OFF=		_RUST_BUILD_DOCS=false
 GDB_RUN_DEPENDS=	${LOCALBASE}/bin/gdb:devel/gdb
+LLVM_VER=		13 # chase bundled LLVM
+PORT_LLVM_BUILD_DEPENDS=llvm-config${LLVM_VER}:devel/llvm${LLVM_VER}
+PORT_LLVM_LIB_DEPENDS=	libLLVM-${LLVM_VER}.so:devel/llvm${LLVM_VER}
+PORT_LLVM_VARS=		MAKE_ENV+=RUSTFLAGS="-Lnative=${LOCALBASE}/lib"
 SOURCES_VARS=		_RUST_TOOLS+=src
 WASM_VARS=		_RUST_BUILD_WASM=true \
 			_RUST_TARGETS+=wasm32-unknown-unknown
@@ -137,6 +142,16 @@
 .endif
 .endif
 
+post-patch-PORT_LLVM-on:
+	# ld error: can't create dynamic relocation R_X86_64_32 against
+	# local symbol in readonly segment; recompile object files with
+	# -fPIC or pass '-Wl,-z,notext' to allow text relocations in the output
+	# (-no-pie is not needed when both base and ports were built as PIE)
+	${REINPLACE_CMD} 's|"-pie"|"-no-pie"|' \
+		${WRKSRC}/compiler/rustc_codegen_ssa/src/back/linker.rs
+	# WASM target hardcodes bundled lld
+	${REINPLACE_CMD} 's|"rust-lld"|"wasm-ld${LLVM_VER}"|' \
+		${WRKSRC}/compiler/rustc_target/src/spec/wasm_base.rs
 do-configure:
 # Check that the running kernel has COMPAT_FREEBSD11 required by lang/rust post-ino64
 	@${SETENV} CC="${CC}" OPSYS="${OPSYS}" OSVERSION="${OSVERSION}" WRKDIR="${WRKDIR}" \
@@ -170,7 +185,9 @@
 	@${ECHO_CMD} 'default-linker="${CC}"' >> ${WRKSRC}/config.toml
 	@${ECHO_CMD} 'deny-warnings=false' >> ${WRKSRC}/config.toml
 	@${ECHO_CMD} 'verbose-tests=true' >> ${WRKSRC}/config.toml
+.if !${PORT_OPTIONS:MPORT_LLVM}
 	@${ECHO_CMD} 'lld=${_RUST_BUILD_WASM}' >> ${WRKSRC}/config.toml
+.endif
 	@${ECHO_CMD} '[llvm]' >> ${WRKSRC}/config.toml
 .if defined(WITH_CCACHE_BUILD) && !defined(NO_CCACHE)
 	@${ECHO_CMD} 'ccache="${CCACHE_BIN}"' >> ${WRKSRC}/config.toml
@@ -204,6 +221,9 @@
 .else
 	@${ECHO_CMD} 'linker="${CC}"' >> ${WRKSRC}/config.toml
 .endif
+.if ${PORT_OPTIONS:MPORT_LLVM}
+	@${ECHO_CMD} 'llvm-config="${LOCALBASE}/bin/llvm-config${LLVM_VER}"' >> ${WRKSRC}/config.toml
+.endif
 .endfor
 	@${ECHO_CMD} '[dist]' >> ${WRKSRC}/config.toml
 	@${ECHO_CMD} 'src-tarball=false' >> ${WRKSRC}/config.toml