diff --git a/libcxx/include/CMakeLists.txt b/libcxx/include/CMakeLists.txt
index 18fec97e51853..79981c59b8706 100644
--- a/libcxx/include/CMakeLists.txt
+++ b/libcxx/include/CMakeLists.txt
@@ -231,8 +231,8 @@ add_library(cxx-headers INTERFACE)
 add_dependencies(cxx-headers generate-cxx-headers ${LIBCXX_CXX_ABI_HEADER_TARGET})
 # TODO: Use target_include_directories once we figure out why that breaks the runtimes build
 if("${CMAKE_CXX_COMPILER_ID}" STREQUAL "MSVC" OR "${CMAKE_CXX_SIMULATE_ID}" STREQUAL "MSVC")
-  target_compile_options(cxx-headers INTERFACE /I "${LIBCXX_GENERATED_INCLUDE_DIR}"
-                                     INTERFACE /I "${LIBCXX_GENERATED_INCLUDE_TARGET_DIR}")
+  target_compile_options(cxx-headers INTERFACE /I${LIBCXX_GENERATED_INCLUDE_DIR}
+                                     INTERFACE /I${LIBCXX_GENERATED_INCLUDE_TARGET_DIR})
 else()
   target_compile_options(cxx-headers INTERFACE -I${LIBCXX_GENERATED_INCLUDE_DIR}
                                      INTERFACE -I${LIBCXX_GENERATED_INCLUDE_TARGET_DIR})