diff --git a/build/mach_bootstrap.py b/build/mach_bootstrap.py
index c67637c9412a..fb0dc3272bfa 100644
--- a/build/mach_bootstrap.py
+++ b/build/mach_bootstrap.py
@@ -131,6 +131,7 @@ def bootstrap(topsrcdir, mozilla_dir=None):
             os.makedirs(state_env_dir, mode=0o770)
             print('Please re-run mach.')
             sys.exit(1)
+        state_dir = state_env_dir
     else:
         if not os.path.exists(state_user_dir):
             print(STATE_DIR_FIRST_RUN.format(userdir=state_user_dir))
@@ -146,6 +147,7 @@ def bootstrap(topsrcdir, mozilla_dir=None):
             os.mkdir(state_user_dir)
             print('Please re-run mach.')
             sys.exit(1)
+        state_dir = state_user_dir
 
     try:
         import mach.main
@@ -153,7 +155,12 @@ def bootstrap(topsrcdir, mozilla_dir=None):
         sys.path[0:0] = [os.path.join(mozilla_dir, path) for path in SEARCH_PATHS]
         import mach.main
 
+    def populate_context(context):
+        context.state_dir = state_dir
+
     mach = mach.main.Mach(topsrcdir)
+    mach.populate_context_handler = populate_context
+
     for category, meta in CATEGORIES.items():
         mach.define_category(category, meta['short'], meta['long'],
             meta['priority'])
diff --git a/python/mach/mach/base.py b/python/mach/mach/base.py
index fea6d38869e7..c21962678fd4 100644
--- a/python/mach/mach/base.py
+++ b/python/mach/mach/base.py
@@ -4,11 +4,16 @@
 
 from __future__ import unicode_literals
 
-from collections import namedtuple
 
-# Holds mach run-time state so it can easily be passed to command providers.
-CommandContext = namedtuple('CommandContext', ['topdir', 'cwd',
-    'settings', 'log_manager', 'commands'])
+class CommandContext(object):
+    """Holds run-time state so it can easily be passed to command providers."""
+    def __init__(self, topdir=None, cwd=None, settings=None, log_manager=None,
+        commands=None):
+        self.topdir = topdir
+        self.cwd = cwd
+        self.settings = settings
+        self.log_manager = log_manager
+        self.commands = commands
 
 
 class MachError(Exception):
diff --git a/python/mach/mach/main.py b/python/mach/mach/main.py
index 2b6b27334dff..ed22533f5b67 100644
--- a/python/mach/mach/main.py
+++ b/python/mach/mach/main.py
@@ -127,7 +127,20 @@ class ArgumentParser(argparse.ArgumentParser):
 
 @CommandProvider
 class Mach(object):
-    """Contains code for the command-line `mach` interface."""
+    """Main mach driver type.
+
+    This type is responsible for holding global mach state and dispatching
+    a command from arguments.
+
+    The following attributes may be assigned to the instance to influence
+    behavior:
+
+        populate_context_handler -- If defined, it must be a callable. The
+            callable will be called with the mach.base.CommandContext instance
+            as its single argument right before command dispatch. This allows
+            modification of the context instance and thus passing of
+            arbitrary data to command handlers.
+    """
 
     USAGE = """%(prog)s [global arguments] command [command arguments]
 
@@ -154,6 +167,8 @@ To see more help for a specific command, run:
         self.logger = logging.getLogger(__name__)
         self.settings = ConfigSettings()
 
+        self.populate_context_handler = None
+
         self.log_manager.register_structured_logger(self.logger)
 
     def load_commands_from_directory(self, path):
@@ -303,6 +318,9 @@ To see more help for a specific command, run:
             settings=self.settings, log_manager=self.log_manager,
             commands=Registrar)
 
+        if self.populate_context_handler:
+            self.populate_context_handler(context)
+
         handler = getattr(args, 'mach_handler')
         cls = handler.cls