diff --git a/ci/x86_64-linux-debug.sh b/ci/x86_64-linux-debug.sh
index 69cd569879e2618c291d7621f8560489045847cc..bbab0c564deebd153399403bcf0301a80e054a94 100755
--- a/ci/x86_64-linux-debug.sh
+++ b/ci/x86_64-linux-debug.sh
@@ -20,6 +20,14 @@ git config core.abbrev 9
 git fetch --unshallow || true
 git fetch --tags
 
+# Test building from source without LLVM.
+git clean -fd
+rm -rf zig-out
+cc -o bootstrap bootstrap.c
+./bootstrap build -Dno-lib
+# In order to run these behavior tests we need to move the `@cImport` ones to somewhere else.
+# ./zig-out/bin/zig test test/behavior.zig
+
 export CC="$ZIG cc -target $TARGET -mcpu=$MCPU"
 export CXX="$ZIG c++ -target $TARGET -mcpu=$MCPU"
 
diff --git a/ci/x86_64-linux-release.sh b/ci/x86_64-linux-release.sh
index 421fb89ba735290ff2f637cb6b36072eb34b526c..61320ce0f9ac2afbada952157e43881f94de7ab6 100755
--- a/ci/x86_64-linux-release.sh
+++ b/ci/x86_64-linux-release.sh
@@ -20,6 +20,14 @@ git config core.abbrev 9
 git fetch --unshallow || true
 git fetch --tags
 
+# Test building from source without LLVM.
+git clean -fd
+rm -rf zig-out
+cc -o bootstrap bootstrap.c
+./bootstrap build -Dno-lib
+# In order to run these behavior tests we need to move the `@cImport` ones to somewhere else.
+# ./zig-out/bin/zig test test/behavior.zig
+
 export CC="$ZIG cc -target $TARGET -mcpu=$MCPU"
 export CXX="$ZIG c++ -target $TARGET -mcpu=$MCPU"