Index: cfe/trunk/tools/libclang/CMakeLists.txt
===================================================================
--- cfe/trunk/tools/libclang/CMakeLists.txt
+++ cfe/trunk/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 +118,11 @@
       PROPERTIES
       VERSION ${LIBCLANG_LIBRARY_VERSION}
       DEFINE_SYMBOL _CINDEX_LIB_)
+    if(LLVM_ENABLE_MODULES)
+      target_compile_options(libclang PRIVATE
+        "-fmodules-ignore-macro=_CINDEX_LIB_"
+        )
+    endif()
   endif()
 endif()
 
Index: llvm/trunk/lib/Fuzzer/CMakeLists.txt
===================================================================
--- llvm/trunk/lib/Fuzzer/CMakeLists.txt
+++ llvm/trunk/lib/Fuzzer/CMakeLists.txt
@@ -26,6 +26,10 @@
   set(CMAKE_CXX_FLAGS "${LIBFUZZER_FLAGS_BASE} -fno-sanitize-coverage=trace-pc-guard,edge,trace-cmp,indirect-calls,8bit-counters -Werror")
 endif()
 
+if(LLVM_ENABLE_MODULES)
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fno-modules")
+endif()
+
 # Compile libFuzzer if the compilation is specifically requested, OR
 # if the platform is known to be working.
 if ( LLVM_USE_SANITIZE_COVERAGE OR CMAKE_SYSTEM_NAME MATCHES "Darwin|Linux" )
Index: llvm/trunk/tools/gold/CMakeLists.txt
===================================================================
--- llvm/trunk/tools/gold/CMakeLists.txt
+++ llvm/trunk/tools/gold/CMakeLists.txt
@@ -7,6 +7,10 @@
   # ABI compatibility.
   add_definitions( -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 )
 
+  if(LLVM_ENABLE_MODULES)
+    list(APPEND LLVM_COMPILE_FLAGS "-fno-modules")
+  endif()
+
   set(LLVM_LINK_COMPONENTS
      ${LLVM_TARGETS_TO_BUILD}
      Linker
Index: llvm/trunk/tools/llvm-config/CMakeLists.txt
===================================================================
--- llvm/trunk/tools/llvm-config/CMakeLists.txt
+++ llvm/trunk/tools/llvm-config/CMakeLists.txt
@@ -59,6 +59,12 @@
 # Set build-time environment(s).
 add_definitions(-DCMAKE_CFG_INTDIR="${CMAKE_CFG_INTDIR}")
 
+if(LLVM_ENABLE_MODULES)
+  target_compile_options(llvm-config PUBLIC
+    "-fmodules-ignore-macro=CMAKE_CFG_INTDIR"
+    )
+endif()
+
 # Add the dependency on the generation step.
 add_file_dependencies(${CMAKE_CURRENT_SOURCE_DIR}/llvm-config.cpp ${BUILDVARIABLES_OBJPATH})
 
Index: llvm/trunk/unittests/Support/DynamicLibrary/CMakeLists.txt
===================================================================
--- llvm/trunk/unittests/Support/DynamicLibrary/CMakeLists.txt
+++ llvm/trunk/unittests/Support/DynamicLibrary/CMakeLists.txt
@@ -2,6 +2,10 @@
 
 add_library(DynamicLibraryLib STATIC ExportedFuncs.cxx)
 
+if(LLVM_ENABLE_MODULES)
+  target_compile_options(DynamicLibraryLib PRIVATE "-fno-modules")
+endif()
+
 add_llvm_unittest(DynamicLibraryTests DynamicLibraryTest.cpp)
 target_link_libraries(DynamicLibraryTests DynamicLibraryLib)
 export_executable_symbols(DynamicLibraryTests)
@@ -19,6 +23,10 @@
     SUFFIX ".so"
     )
 
+  if(LLVM_ENABLE_MODULES)
+    target_compile_options(${NAME} PRIVATE "-fno-modules")
+  endif()
+
   add_dependencies(DynamicLibraryTests ${NAME})
 endfunction(dynlib_add_module)
 
Index: llvm/trunk/utils/unittest/CMakeLists.txt
===================================================================
--- llvm/trunk/utils/unittest/CMakeLists.txt
+++ llvm/trunk/utils/unittest/CMakeLists.txt
@@ -45,6 +45,11 @@
   list(APPEND LIBS pthread)
 endif()
 
+# -frtti
+if(LLVM_ENABLE_MODULES)
+  list(APPEND LLVM_COMPILE_FLAGS "-fno-modules")
+endif()
+
 add_llvm_library(gtest
   googletest/src/gtest-all.cc
   googlemock/src/gmock-all.cc