diff --git a/tools/libclang/CMakeLists.txt b/tools/libclang/CMakeLists.txt
index 2dd6703..a28499c 100644
--- a/tools/libclang/CMakeLists.txt
+++ b/tools/libclang/CMakeLists.txt
@@ -51,6 +51,9 @@
   add_definitions(-DCLANG_TOOL_EXTRA_BUILD)
   list(APPEND LIBS clangTidyPlugin)
   list(APPEND LIBS clangIncludeFixerPlugin)
+  if(LLVM_ENABLE_MODULES)
+    list(APPEND LLVM_COMPILE_FLAGS "-fmodules-ignore-macro=CLANG_TOOL_EXTRA_BUILD")
+  endif()
 endif ()
 
 find_library(DL_LIBRARY_PATH dl)
@@ -115,6 +118,12 @@
       PROPERTIES
       VERSION ${LIBCLANG_LIBRARY_VERSION}
       DEFINE_SYMBOL _CINDEX_LIB_)
+    # FIXME: _CINDEX_LIB_ affects dllexport/dllimport on Win32.
+    if(LLVM_ENABLE_MODULES AND NOT WIN32)
+      target_compile_options(libclang PRIVATE
+        "-fmodules-ignore-macro=_CINDEX_LIB_"
+        )
+    endif()
   endif()
 endif()