diff --git a/config.sh b/config.sh
index 9bfff744a66..43280c09141 100644
--- a/config.sh
+++ b/config.sh
@@ -12,7 +12,7 @@ fi
 
 TARGET_TRIPLE=$(rustc -vV | grep host | cut -d: -f2 | tr -d " ")
 
-export RUSTFLAGS='-Zalways-encode-mir -Cpanic=abort -Cdebuginfo=2 -Zcodegen-backend='$(pwd)'/target/'$CHANNEL'/librustc_codegen_cranelift.'$dylib_ext' --sysroot '$(pwd)'/build_sysroot/sysroot'
+export RUSTFLAGS='-Cpanic=abort -Cdebuginfo=2 -Zcodegen-backend='$(pwd)'/target/'$CHANNEL'/librustc_codegen_cranelift.'$dylib_ext' --sysroot '$(pwd)'/build_sysroot/sysroot'
 RUSTC="rustc $RUSTFLAGS -L crate=target/out --out-dir target/out"
 export RUSTC_LOG=warn # display metadata load errors