Index: llvm/trunk/cmake/config-ix.cmake
===================================================================
--- llvm/trunk/cmake/config-ix.cmake
+++ llvm/trunk/cmake/config-ix.cmake
@@ -640,7 +640,8 @@
 string(REPLACE " " ";" LLVM_BINDINGS_LIST "${LLVM_BINDINGS}")
 
 function(find_python_module module)
-  string(TOUPPER ${module} module_upper)
+  string(REPLACE "." "_" module_name ${module})
+  string(TOUPPER ${module_name} module_upper)
   set(FOUND_VAR PY_${module_upper}_FOUND)
 
   execute_process(COMMAND "${PYTHON_EXECUTABLE}" "-c" "import ${module}"
@@ -658,13 +659,16 @@
 
 set (PYTHON_MODULES
   pygments
+  # Some systems still don't have pygments.lexers.c_cpp which was introduced in
+  # version 2.0 in 2014...
+  pygments.lexers.c_cpp
   yaml
   )
 foreach(module ${PYTHON_MODULES})
   find_python_module(${module})
 endforeach()
 
-if(PY_PYGMENTS_FOUND AND PY_YAML_FOUND)
+if(PY_PYGMENTS_FOUND AND PY_PYGMENTS_LEXERS_C_CPP_FOUND AND PY_YAML_FOUND)
   set (LLVM_HAVE_OPT_VIEWER_MODULES 1)
 else()
   set (LLVM_HAVE_OPT_VIEWER_MODULES 0)