diff --git a/rust.spec b/rust.spec
index 390db43..d46d6e9 100644
--- a/rust.spec
+++ b/rust.spec
@@ -78,7 +78,7 @@
 
 # Debuginfo can exhaust memory on these architecture workers
 %ifarch  %{arm} %{ix86}
-%define codegen_units --set rust.codegen-units=2
+%define codegen_units --set rust.codegen-units=4
 %define debug_info --disable-debuginfo --disable-debuginfo-only-std --disable-debuginfo-tools --disable-debuginfo-lines
 %else
 %define codegen_units --set rust.codegen-units=0
@@ -86,9 +86,11 @@
 %endif
 # Use hardening ldflags.
 %global rustflags -Clink-arg=-Wl,-z,relro,-z,now
-# Cargo use system libs
+# Cargo use system libs if not bootstrapping
+%if !%with rust_bootstrap
 %global cargo_git LIBGIT2_SYS_USE_PKG_CONFIG=1
 %global cargo_ssh LIBSSH2_SYS_USE_PKG_CONFIG=1
+%endif
 # eliminate complain from RPMlint
 %global nocomplain CPPFLAGS="%{optflags}"
 
@@ -142,8 +144,8 @@ ExclusiveArch:  x86_64 %{arm} aarch64 ppc64 ppc64le s390x %{ix86}
 %ifarch %{ix86}
 ExclusiveArch:  i686
 %endif
+# Reall LLVM minimum version should be 7.x, but rust has a fallback mode
 %if !%with bundled_llvm
-# LLVM gives incorrect C++ flags for GCC
 BuildRequires:  llvm-devel >= 6.0
 %endif
 %if !%with rust_bootstrap