diff --git a/rust.spec b/rust.spec
index a0d1851..e5b933f 100644
--- a/rust.spec
+++ b/rust.spec
@@ -171,6 +171,11 @@ BuildRequires:  cmake >= 2.8.11
 %if 0%{?epel} == 7
 %global llvm llvm9.0
 %endif
+%if 0%{?fedora} == 34
+# aarch64 is hanging with LLVM 12-rc1, but it's fine with 12-final on rawhide.
+# Fall back to LLVM 11 on f34 for now...
+%global llvm llvm11
+%endif
 %if %defined llvm
 %global llvm_root %{_libdir}/%{llvm}
 %else