diff --git a/Modules/FindBISON.cmake b/Modules/FindBISON.cmake
index 313e54cb8c..a2c37cfe8f 100644
--- a/Modules/FindBISON.cmake
+++ b/Modules/FindBISON.cmake
@@ -330,7 +330,27 @@ if(BISON_EXECUTABLE)
       endif()
       unset(_BISON_CMP0088)
 
+      # Bison cannot create output directories. Create any missing determined
+      # directories where the files will be generated if they don't exist yet.
+      set(_BisonMakeDirectoryCommand "")
+      foreach(output IN LISTS BISON_TARGET_outputs)
+        cmake_path(GET output PARENT_PATH dir)
+        if(dir)
+          list(APPEND _BisonMakeDirectoryCommand ${dir})
+        endif()
+        unset(dir)
+      endforeach()
+      if(_BisonMakeDirectoryCommand)
+        list(REMOVE_DUPLICATES _BisonMakeDirectoryCommand)
+        list(
+          PREPEND
+          _BisonMakeDirectoryCommand
+          COMMAND ${CMAKE_COMMAND} -E make_directory
+        )
+      endif()
+
       add_custom_command(OUTPUT ${BISON_TARGET_outputs}
+        ${_BisonMakeDirectoryCommand}
         COMMAND ${BISON_EXECUTABLE} ${BISON_TARGET_cmdopt} -o ${BisonOutput} ${_BisonInput}
         VERBATIM
         DEPENDS ${_BisonInput}
@@ -350,7 +370,7 @@ if(BISON_EXECUTABLE)
       set(BISON_${Name}_OUTPUT_HEADER "${BISON_TARGET_output_header}")
 
       unset(_BisonInput)
-
+      unset(_BisonMakeDirectoryCommand)
     endif()
   endmacro()
   #
diff --git a/Modules/FindFLEX.cmake b/Modules/FindFLEX.cmake
index d9d0afa56b..9cbe721cde 100644
--- a/Modules/FindFLEX.cmake
+++ b/Modules/FindFLEX.cmake
@@ -268,8 +268,28 @@ if(FLEX_EXECUTABLE)
         list(APPEND _flex_EXE_OPTS --header-file=${_flex_OUTPUT_HEADER_ABS})
       endif()
 
+      # Flex cannot create output directories. Create any missing determined
+      # directories where the files will be generated if they don't exist yet.
+      set(_flex_MAKE_DIRECTORY_COMMAND "")
+      foreach(output IN LISTS _flex_TARGET_OUTPUTS)
+        cmake_path(GET output PARENT_PATH dir)
+        if(dir)
+          list(APPEND _flex_MAKE_DIRECTORY_COMMAND ${dir})
+        endif()
+        unset(dir)
+      endforeach()
+      if(_flex_MAKE_DIRECTORY_COMMAND)
+        list(REMOVE_DUPLICATES _flex_MAKE_DIRECTORY_COMMAND)
+        list(
+          PREPEND
+          _flex_MAKE_DIRECTORY_COMMAND
+          COMMAND ${CMAKE_COMMAND} -E make_directory
+        )
+      endif()
+
       get_filename_component(_flex_EXE_NAME_WE "${FLEX_EXECUTABLE}" NAME_WE)
       add_custom_command(OUTPUT ${_flex_TARGET_OUTPUTS}
+        ${_flex_MAKE_DIRECTORY_COMMAND}
         COMMAND ${FLEX_EXECUTABLE} ${_flex_EXE_OPTS} -o${_flex_OUTPUT} ${_flex_INPUT}
         VERBATIM
         DEPENDS ${_flex_INPUT}
@@ -287,12 +307,12 @@ if(FLEX_EXECUTABLE)
       unset(_flex_EXE_NAME_WE)
       unset(_flex_EXE_OPTS)
       unset(_flex_INPUT)
+      unset(_flex_MAKE_DIRECTORY_COMMAND)
       unset(_flex_OUTPUT)
       unset(_flex_OUTPUT_HEADER)
       unset(_flex_OUTPUT_HEADER_ABS)
       unset(_flex_TARGET_OUTPUTS)
       unset(_flex_WORKING_DIR)
-
     endif()
   endmacro()
   #============================================================