diff --git a/ci/x86_64-linux-debug-llvm.sh b/ci/x86_64-linux-debug-llvm.sh
index 3a69718c1be6ebcb0c95616f190abdbc9f7bf2f8..a27e9d356598c1e75fe4081d903dbfa24e44e04f 100755
--- a/ci/x86_64-linux-debug-llvm.sh
+++ b/ci/x86_64-linux-debug-llvm.sh
@@ -66,3 +66,14 @@ stage3-debug/bin/zig build test docs \
   --zig-lib-dir "$PWD/../lib" \
   -Denable-superhtml \
   --test-timeout 12m
+
+stage3-debug/bin/zig build \
+  --prefix stage4-debug \
+  -Duse-llvm \
+  -Denable-llvm \
+  -Dno-lib \
+  -Dtarget=$TARGET \
+  -Duse-zig-libcxx \
+  -Dversion-string="$(stage3-debug/bin/zig version)"
+
+stage4-debug/bin/zig test ../test/behavior.zig
diff --git a/ci/x86_64-linux-debug.sh b/ci/x86_64-linux-debug.sh
index 0fc6605e59938d9d23068c0ef1e781699b51a865..734b4d095259044a5d57ccc2429616f04898322c 100755
--- a/ci/x86_64-linux-debug.sh
+++ b/ci/x86_64-linux-debug.sh
@@ -66,3 +66,13 @@ stage3-debug/bin/zig build test docs \
   --zig-lib-dir "$PWD/../lib" \
   -Denable-superhtml \
   --test-timeout 10m
+
+stage3-debug/bin/zig build \
+  --prefix stage4-debug \
+  -Denable-llvm \
+  -Dno-lib \
+  -Dtarget=$TARGET \
+  -Duse-zig-libcxx \
+  -Dversion-string="$(stage3-debug/bin/zig version)"
+
+stage4-debug/bin/zig test ../test/behavior.zig