--- a/python/mozbuild/mozbuild/base.py
+++ b/python/mozbuild/mozbuild/base.py
@@ -243,16 +243,21 @@ class MozbuildObject(object):
         params = {
             'args': args,
             'line_handler': line_handler,
             'append_env': append_env,
             'explicit_env': explicit_env,
             'log_level': logging.INFO,
             'require_unix_environment': True,
             'ignore_errors': ignore_errors,
+
+            # Make manages its children, so mozprocess doesn't need to bother.
+            # Having mozprocess manage children can also have side-effects when
+            # building on Windows. See bug 796840.
+            'ignore_children': True,
         }
 
         if log:
             params['log_name'] = 'make'
 
         fn(**params)
 
     @property
@@ -279,31 +284,33 @@ class MozbuildObject(object):
         self._run_command(cwd=self.topsrcdir, **args)
 
     def _run_command_in_objdir(self, **args):
         self._run_command(cwd=self.topobjdir, **args)
 
     def _run_command(self, args=None, cwd=None, append_env=None,
         explicit_env=None, log_name=None, log_level=logging.INFO,
         line_handler=None, require_unix_environment=False,
-        ignore_errors=False):
+        ignore_errors=False, ignore_children=False):
         """Runs a single command to completion.
 
         Takes a list of arguments to run where the first item is the
         executable. Runs the command in the specified directory and
         with optional environment variables.
 
         append_env -- Dict of environment variables to append to the current
             set of environment variables.
         explicit_env -- Dict of environment variables to set for the new
             process. Any existing environment variables will be ignored.
 
         require_unix_environment if True will ensure the command is executed
         within a UNIX environment. Basically, if we are on Windows, it will
         execute the command via an appropriate UNIX-like shell.
+
+        ignore_children is proxied to mozprocess's ignore_children.
         """
         args = self._normalize_command(args, require_unix_environment)
 
         self.log(logging.INFO, 'process', {'args': args}, ' '.join(args))
 
         def handleLine(line):
             # Converts str to unicode on Python 2 and bytes to str on Python 3.
             if isinstance(line, bytes):
@@ -324,17 +331,18 @@ class MozbuildObject(object):
             use_env.update(os.environ)
 
             if append_env:
                 use_env.update(append_env)
 
         self.log(logging.DEBUG, 'process', {'env': use_env}, 'Environment: {env}')
 
         p = ProcessHandlerMixin(args, cwd=cwd, env=use_env,
-            processOutputLine=[handleLine], universal_newlines=True)
+            processOutputLine=[handleLine], universal_newlines=True,
+            ignore_children=ignore_children)
         p.run()
         p.processOutput()
         status = p.wait()
 
         if status != 0 and not ignore_errors:
             raise Exception('Process executed with non-0 exit code: %s' % args)
 
     def _normalize_command(self, args, require_unix_environment):