diff --git a/python/mozbuild/mozbuild/action/generate_symbols_file.py b/python/mozbuild/mozbuild/action/generate_symbols_file.py
index 9f76f9823e3f..ba1d562a9bc6 100644
--- a/python/mozbuild/mozbuild/action/generate_symbols_file.py
+++ b/python/mozbuild/mozbuild/action/generate_symbols_file.py
@@ -4,18 +4,30 @@
 
 from __future__ import absolute_import, print_function, unicode_literals
 
+import argparse
 import buildconfig
 import os
 from StringIO import StringIO
 from mozbuild.preprocessor import Preprocessor
+from mozbuild.util import DefinesAction
 
 
-def generate_symbols_file(output, input):
+def generate_symbols_file(output, *args):
     ''' '''
-    input = os.path.abspath(input)
+    parser = argparse.ArgumentParser()
+    parser.add_argument('input')
+    parser.add_argument('-D', action=DefinesAction)
+    parser.add_argument('-U', action='append', default=[])
+    args = parser.parse_args(args)
+    input = os.path.abspath(args.input)
 
     pp = Preprocessor()
     pp.context.update(buildconfig.defines)
+    if args.D:
+        pp.context.update(args.D)
+    for undefine in args.U:
+        if undefine in pp.context:
+            del pp.context[undefine]
     # Hack until MOZ_DEBUG_FLAGS are simply part of buildconfig.defines
     if buildconfig.substs['MOZ_DEBUG']:
         pp.context['DEBUG'] = '1'
diff --git a/python/mozbuild/mozbuild/frontend/emitter.py b/python/mozbuild/mozbuild/frontend/emitter.py
index ac364b3ed398..0c1e99562422 100644
--- a/python/mozbuild/mozbuild/frontend/emitter.py
+++ b/python/mozbuild/mozbuild/frontend/emitter.py
@@ -538,7 +538,7 @@ class TreeMetadataEmitter(LoggingMixin):
                         'action', 'generate_symbols_file.py')
                     yield GeneratedFile(context, script,
                         'generate_symbols_file', lib.symbols_file,
-                        [symbols_file.full_path])
+                        [symbols_file.full_path], lib.defines.get_defines())
             if static_lib:
                 lib = StaticLibrary(context, libname, **static_args)
                 self._libs[libname].append(lib)