diff --git a/clang/docs/LibASTMatchersTutorial.rst b/clang/docs/LibASTMatchersTutorial.rst
index 37c9f178fa8df..2a58502a8de4e 100644
--- a/clang/docs/LibASTMatchersTutorial.rst
+++ b/clang/docs/LibASTMatchersTutorial.rst
@@ -50,7 +50,7 @@ Okay. Now we'll build Clang!
 
       cd ~/clang-llvm
       mkdir build && cd build
-      cmake -G Ninja ../llvm -DLLVM_ENABLE_PROJECTS="clang;clang-tools-extra" -DLLVM_BUILD_TESTS=ON  # Enable tests; default is off.
+      cmake -G Ninja ../llvm -DLLVM_ENABLE_PROJECTS="clang;clang-tools-extra" -DCMAKE_BUILD_TYPE=Release -DLLVM_BUILD_TESTS=ON
       ninja
       ninja check       # Test LLVM only.
       ninja clang-test  # Test Clang only.