diff --git a/HISTORY.rst b/HISTORY.rst
index 2b10f752..9a9b8145 100644
--- a/HISTORY.rst
+++ b/HISTORY.rst
@@ -10,11 +10,12 @@ PlatformIO 4.0
 * **Project Management**
 
   - Unified workspace storage (`workspace_dir <http://docs.platformio.org/page/projectconf/section_platformio.html#workspace-dir>`__ -> ``.pio``) for PlatformIO Build System, Library Manager, and other internal services (`issue #1778 <https://github.com/platformio/platformio-core/issues/1778>`_)
+  - Switched to workspace ``.pio/build`` folder for build artifacts instead of ``.pioenvs``
   - Share common (global) options between build environments using ``[env]`` section in `"platformio.ini" (Project Configuration File) <https://docs.platformio.org/page/projectconf.html>`__ (`issue #1643 <https://github.com/platformio/platformio-core/issues/1643>`_)
   - Include external configuration files in `"platformio.ini" (Project Configuration File) <https://docs.platformio.org/page/projectconf.html>`__ with `extra_configs <http://docs.platformio.org/page/projectconf/section_platformio.html#extra-configs>`__ option (`issue #1590 <https://github.com/platformio/platformio-core/issues/1590>`_)
   - Override default `"platformio.ini" (Project Configuration File) <https://docs.platformio.org/page/projectconf.html>`__ with a custom using ``-c, --project-conf`` option for `platformio run <http://docs.platformio.org/page/userguide/cmd_run.html>`__, `platformio debug <http://docs.platformio.org/page/userguide/cmd_debug.html>`__, or `platformio test <http://docs.platformio.org/page/userguide/cmd_test.html>`__ commands (`issue #1913 <https://github.com/platformio/platformio-core/issues/1913>`_)
   - Custom project ``***_dir`` options declared in "platformio" section of `"platformio.ini" (Project Configuration File) <https://docs.platformio.org/page/projectconf.html>`__ have higher priority than `Environment variables <http://docs.platformio.org/page/envvars.html>`__
-  - Use workspace ``.pio/build`` folder for build artifacts instead of ``.pioenvs``
+  - Added new `monitor_flags <http://docs.platformio.org/page/projectconf/section_env_monitor.html#monitor-flags>`__ option to `"platformio.ini" (Project Configuration File) <https://docs.platformio.org/page/projectconf.html>`__ which allows passing extra flags and options to `platformio device monitor <http://docs.platformio.org/page/userguide/cmd_device.html#cmd-device-monitor>`__ command (`issue #2165 <https://github.com/platformio/platformio-core/issues/2165>`_)
 
 * **Library Management**
 
@@ -22,7 +23,7 @@ PlatformIO 4.0
   - Install all project dependencies declared via `lib_deps <http://docs.platformio.org/page/projectconf/section_env_library.html#lib-deps>`__ option using a simple `platformio lib install <http://docs.platformio.org/page/userguide/lib/cmd_install.html>`__ command (`issue #2147 <https://github.com/platformio/platformio-core/issues/2147>`_)
   - Use isolated library dependency storage per project build environment (`issue #1696 <https://github.com/platformio/platformio-core/issues/1696>`_)
   - Override default source and include directories for a library via `library.json <http://docs.platformio.org/page/librarymanager/config.html>`__ manifest using ``includeDir`` and ``srcDir`` fields
-  - Use workspace ``.pio/libdeps`` folder for project dependencies instead of ``.piolibdeps``
+  - Switched to workspace ``.pio/libdeps`` folder for project dependencies instead of ``.piolibdeps``
 
 * **Infrastructure**
 
@@ -43,7 +44,7 @@ PlatformIO 3.0
 
 * Support custom CMake configuration for CLion IDE using ``CMakeListsUser.txt`` file
 * Fixed an issue with hardcoded C stadard version when generating project for CLion IDE (`issue #2527 <https://github.com/platformio/platformio-core/issues/2527>`_)
-* Fixed "systemd-udevd" warnings in `99-platformio-udev.rules <http://docs.platformio.org/en/latest/faq.html#platformio-udev-rules>`__ (`issue #2442 <https://github.com/platformio/platformio-core/issues/2442>`_)
+* Fixed "systemd-udevd" warnings in `99-platformio-udev.rules <http://docs.platformio.org/page/faq.html#platformio-udev-rules>`__ (`issue #2442 <https://github.com/platformio/platformio-core/issues/2442>`_)
 * Fixed an issue when ``-U`` in ``build_flags`` does not remove macro previously defined via ``-D`` flag (`issue #2508 <https://github.com/platformio/platformio-core/issues/2508>`_)
 * Fixed an issue for Project Generator when include path search order is inconsistent to what passed to the compiler (`issue #2509 <https://github.com/platformio/platformio-core/issues/2509>`_)
 
diff --git a/docs b/docs
index 401b1447..158fb3c0 160000
--- a/docs
+++ b/docs
@@ -1 +1 @@
-Subproject commit 401b1447a3667bf256d6d13718bc8454c7f76888
+Subproject commit 158fb3c0484586ef4b87dbd6ef7d780cbe74786c
diff --git a/platformio/commands/device.py b/platformio/commands/device.py
index e75660ea..9f80062e 100644
--- a/platformio/commands/device.py
+++ b/platformio/commands/device.py
@@ -162,16 +162,20 @@ def device_list(  # pylint: disable=too-many-branches
     "--environment",
     help="Load configuration from `platformio.ini` and specified environment")
 def device_monitor(**kwargs):  # pylint: disable=too-many-branches
+    custom_monitor_flags = []
     try:
-        monitor_options = get_project_options(kwargs['project_dir'],
-                                              kwargs['environment'])
-        if monitor_options:
+        env_options = get_project_options(kwargs['project_dir'],
+                                          kwargs['environment'])
+        if "monitor_flags" in env_options:
+            custom_monitor_flags = ProjectConfig.parse_multi_values(
+                env_options['monitor_flags'])
+        if env_options:
             for k in ("port", "speed", "rts", "dtr"):
                 k2 = "monitor_%s" % k
                 if k == "speed":
                     k = "baud"
-                if kwargs[k] is None and k2 in monitor_options:
-                    kwargs[k] = monitor_options[k2]
+                if kwargs[k] is None and k2 in env_options:
+                    kwargs[k] = env_options[k2]
                     if k != "port":
                         kwargs[k] = int(kwargs[k])
     except exception.NotPlatformIOProject:
@@ -182,11 +186,13 @@ def device_monitor(**kwargs):  # pylint: disable=too-many-branches
         if len(ports) == 1:
             kwargs['port'] = ports[0]['port']
 
-    sys.argv = ["monitor"]
+    sys.argv = ["monitor"] + custom_monitor_flags
     for k, v in kwargs.items():
         if k in ("port", "baud", "rts", "dtr", "environment", "project_dir"):
             continue
         k = "--" + k.replace("_", "-")
+        if k in custom_monitor_flags:
+            continue
         if isinstance(v, bool):
             if v:
                 sys.argv.append(k)
@@ -196,6 +202,8 @@ def device_monitor(**kwargs):  # pylint: disable=too-many-branches
         else:
             sys.argv.extend([k, str(v)])
 
+    print(sys.argv)
+
     try:
         miniterm.main(
             default_port=kwargs['port'],
diff --git a/platformio/project/config.py b/platformio/project/config.py
index 7b5baac0..d67df78b 100644
--- a/platformio/project/config.py
+++ b/platformio/project/config.py
@@ -86,6 +86,7 @@ KNOWN_ENV_OPTIONS = [
     "monitor_speed",
     "monitor_rts",
     "monitor_dtr",
+    "monitor_flags",
 
     # Library
     "lib_deps",