diff --git a/libc/test/utils/tools/CMakeLists.txt b/libc/test/utils/tools/CMakeLists.txt
--- a/libc/test/utils/tools/CMakeLists.txt
+++ b/libc/test/utils/tools/CMakeLists.txt
@@ -33,4 +33,10 @@
   target_link_libraries(${target_name} PRIVATE LLVMSupport)
 endfunction()
 
+# Build the gtest library needed for unittests if we do not have it already.
+if (EXISTS ${LLVM_THIRD_PARTY_DIR}/unittest AND NOT TARGET llvm_gtest)
+  include_directories(${LLVM_LIBC_INCLUDE_DIRS})
+  add_subdirectory(${LLVM_THIRD_PARTY_DIR}/unittest third-party/unittest)
+endif()
+
 add_subdirectory(WrapperGen)
diff --git a/libc/test/utils/tools/WrapperGen/CMakeLists.txt b/libc/test/utils/tools/WrapperGen/CMakeLists.txt
--- a/libc/test/utils/tools/WrapperGen/CMakeLists.txt
+++ b/libc/test/utils/tools/WrapperGen/CMakeLists.txt
@@ -4,7 +4,7 @@
     wrappergen_test.cpp   
   ARGS
     --path=${LIBC_SOURCE_DIR}
-    --tool=${CMAKE_BINARY_DIR}/bin/libc-wrappergen
+    --tool=${LLVM_BINARY_DIR}/bin/libc-wrappergen
     --api=${LIBC_SOURCE_DIR}/test/utils/tools/WrapperGen/testapi.td
 )