Index: lldb/bindings/CMakeLists.txt
===================================================================
--- lldb/bindings/CMakeLists.txt
+++ lldb/bindings/CMakeLists.txt
@@ -33,6 +33,10 @@
 )
 
 if (LLDB_ENABLE_PYTHON)
+  if (NOT SWIG_FOUND)
+    message(FATAL_ERROR
+            "The SWIG package is required for Python support in LLDB.")
+  endif()
   add_custom_command(
     OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/LLDBWrapPython.cpp
     OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/lldb.py
@@ -57,6 +61,10 @@
 endif()
 
 if (LLDB_ENABLE_LUA)
+  if (NOT SWIG_FOUND)
+    message(FATAL_ERROR
+            "The SWIG package is required for LUA support in LLDB.")
+  endif()
   add_custom_command(
     OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/LLDBWrapLua.cpp
     DEPENDS ${SWIG_SOURCES}