diff --git a/templates/chisel/nix/gcd/vcs-wrapper.sh b/templates/chisel/nix/gcd/vcs-wrapper.sh
new file mode 100755
index 0000000..4acbe91
--- /dev/null
+++ b/templates/chisel/nix/gcd/vcs-wrapper.sh
@@ -0,0 +1,42 @@
+#!@shell@
+
+_EXTRA_ARGS="$@"
+
+if (( $VERBOSE )); then
+  set -x
+fi
+
+_DATE_BIN=@dateBin@
+_VCS_SIM_BIN=@vcsSimBin@
+_VCS_SIM_DAIDIR=@vcsSimDaidir@
+_VCS_FHS_ENV=@vcsFhsEnv@
+
+_NOW=$("$_DATE_BIN" "+%Y-%m-%d-%H-%M-%S")
+_GCD_SIM_RESULT_DIR=${GCD_SIM_RESULT_DIR:-"gcd-sim-result"}
+_CURRENT="$_GCD_SIM_RESULT_DIR"/all/"$_NOW"
+mkdir -p "$_CURRENT"
+ln -sf "all/$_NOW" "$_GCD_SIM_RESULT_DIR/result"
+
+cp "$_VCS_SIM_BIN" "$_CURRENT/"
+cp -r "$_VCS_SIM_DAIDIR" "$_CURRENT/"
+
+chmod -R +w "$_CURRENT"
+
+pushd "$_CURRENT" >/dev/null
+
+_emu_name=$(basename "$_VCS_SIM_BIN")
+_daidir=$(basename "$_VCS_SIM_DAIDIR")
+
+export LD_LIBRARY_PATH="$PWD/$_daidir:$LD_LIBRARY_PATH"
+
+"$_VCS_FHS_ENV" -c "./$_emu_name $_EXTRA_ARGS" &> >(tee vcs-emu-journal.log)
+
+if (( $DATA_ONLY )); then
+  rm -f "./$_emu_name"
+fi
+
+set -e _emu_name _daidir
+
+popd >/dev/null
+
+echo "VCS emulator finished, result saved in $_GCD_SIM_RESULT_DIR/result"
diff --git a/templates/chisel/nix/gcd/vcs.nix b/templates/chisel/nix/gcd/vcs.nix
index fd8f986..6adae77 100644
--- a/templates/chisel/nix/gcd/vcs.nix
+++ b/templates/chisel/nix/gcd/vcs.nix
@@ -58,9 +58,11 @@ stdenv.mkDerivation (finalAttr: {
     inherit rtl;
 
     tests.simple-sim = runCommand "${binName}-test" { __noChroot = true; } ''
-      # Combine stderr and stdout and redirect them to tee
-      # So that we can have log saving to output and also printing to stdout
-      ${finalAttr.finalPackage}/bin/${binName} &> >(tee $out)
+      mkdir -p "$out"
+
+      export _GCD_SIM_RESULT_DIR="$out"
+      export _DATA_ONLY=1
+      ${finalAttr.finalPackage}/bin/${binName}
     '';
   };
 
@@ -76,14 +78,13 @@ stdenv.mkDerivation (finalAttr: {
     cp ${binName} $out/lib
     cp -r ${binName}.daidir $out/lib
 
-    # We need to carefully handle string escape here, so don't use makeWrapper
-    tee $out/bin/${binName} <<EOF
-    #!${bash}/bin/bash
-    export LD_LIBRARY_PATH="$out/lib/${binName}.daidir:\$LD_LIBRARY_PATH"
-    _argv="\$@"
-    ${vcs-fhs-env}/bin/vcs-fhs-env -c "$out/lib/${binName} \$_argv"
-    EOF
-    chmod +x $out/bin/${binName}
+    substitute ${./vcs-wrapper.sh} $out/bin/${binName} \
+      --subst-var-by shell "${bash}/bin/bash" \
+      # Use coreutil in this stdenv
+      --subst-var-by dateBin "$(command -v date)" \
+      --subst-var-by vcsSimBin "$out/lib/${binName}" \
+      --subst-var-by vcsSimDaidir "$out/lib/${binName}.daidir" \
+      --subst-var-by vcsFhsEnv "${vcs-fhs-env}/bin/vcs-fhs-env"
 
     runHook postInstall
   '';