diff --git a/docs b/docs
index c7591d26..374f5e11 160000
--- a/docs
+++ b/docs
@@ -1 +1 @@
-Subproject commit c7591d260bea5cb04aaab1fd93ca008586f333ea
+Subproject commit 374f5e110f01eebad6065ca9774b831380e0cfb2
diff --git a/platformio/builder/main.py b/platformio/builder/main.py
index 5a5c8676..e6b5d727 100644
--- a/platformio/builder/main.py
+++ b/platformio/builder/main.py
@@ -31,11 +31,11 @@ from SCons.Script import Variables  # pylint: disable=import-error
 from platformio import util
 from platformio.compat import PY2, path_to_unicode
 from platformio.proc import get_pythonexe_path
+from platformio.project.config import ProjectConfig
 from platformio.project.helpers import (
-    get_project_dir, get_project_optional_dir, get_projectbuild_dir,
-    get_projectdata_dir, get_projectinclude_dir, get_projectlib_dir,
-    get_projectlibdeps_dir, get_projectsrc_dir, get_projecttest_dir,
-    get_projectworkspace_dir)
+    get_project_dir, get_projectbuild_dir, get_projectdata_dir,
+    get_projectinclude_dir, get_projectlib_dir, get_projectlibdeps_dir,
+    get_projectsrc_dir, get_projecttest_dir, get_projectworkspace_dir)
 
 AllowSubstExceptions(NameError)
 
@@ -144,7 +144,7 @@ for k in list(commonvars.keys()):
         if isinstance(env[k], bytes):
             env[k] = env[k].decode()
         if k in MULTILINE_VARS:
-            env[k] = util.parse_conf_multi_values(env[k])
+            env[k] = ProjectConfig.parse_multi_values(env[k])
 
 if env.GetOption('clean'):
     env.PioClean(env.subst("$BUILD_DIR"))
@@ -161,18 +161,15 @@ for var in ("BUILD_FLAGS", "SRC_BUILD_FLAGS", "SRC_FILTER", "EXTRA_SCRIPTS",
     if var in ("UPLOAD_PORT", ):
         env[var] = environ.get(k)
         continue
-    env.Append(**{var: util.parse_conf_multi_values(environ.get(k))})
+    env.Append(**{var: ProjectConfig.parse_multi_values(environ.get(k))})
 
-# Configure extra library source directories for LDF
-if get_project_optional_dir("lib_extra_dirs"):
-    env.Prepend(
-        LIBSOURCE_DIRS=util.parse_conf_multi_values(
-            get_project_optional_dir("lib_extra_dirs")))
 env.Prepend(LIBSOURCE_DIRS=env.get("LIB_EXTRA_DIRS", []))
 env['LIBSOURCE_DIRS'] = [
     expanduser(d) if d.startswith("~") else d for d in env['LIBSOURCE_DIRS']
 ]
 
+print(env['LIBSOURCE_DIRS'])
+
 env.LoadPioPlatform(commonvars)
 
 env.SConscriptChdir(0)
diff --git a/platformio/commands/run.py b/platformio/commands/run.py
index 00c2622a..e3085626 100644
--- a/platformio/commands/run.py
+++ b/platformio/commands/run.py
@@ -161,8 +161,8 @@ class EnvironmentProcessor(object):
         for k, v in self.options.items():
             self.options[k] = self.options[k].strip()
             if self.verbose or k in self.DEFAULT_DUMP_OPTIONS:
-                env_dump.append(
-                    "%s: %s" % (k, ", ".join(util.parse_conf_multi_values(v))))
+                env_dump.append("%s: %s" % (k, ", ".join(
+                    ProjectConfig.parse_multi_values(v))))
 
         if not self.silent:
             click.echo("Processing %s (%s)" % (click.style(
@@ -230,7 +230,7 @@ class EnvironmentProcessor(object):
             if "lib_deps" in self.options:
                 _autoinstall_libdeps(
                     self.cmd_ctx,
-                    util.parse_conf_multi_values(self.options['lib_deps']),
+                    ProjectConfig.parse_multi_values(self.options['lib_deps']),
                     self.verbose)
 
         try:
diff --git a/platformio/project/config.py b/platformio/project/config.py
index 419ced01..19842922 100644
--- a/platformio/project/config.py
+++ b/platformio/project/config.py
@@ -54,8 +54,7 @@ KNOWN_PLATFORMIO_OPTIONS = [
     "build_dir",
     "data_dir",
     "test_dir",
-    "boards_dir",
-    "lib_extra_dirs"
+    "boards_dir"
 ]
 
 KNOWN_ENV_OPTIONS = [
@@ -275,17 +274,40 @@ class ProjectConfig(object):
         return self.validate_options() if validate_options else True
 
     def validate_options(self):
-        warnings = set()
-        # check [platformio] section
-        if self._parser.has_section("platformio"):
-            unknown = set(k for k, _ in self.items("platformio")) - set(
-                KNOWN_PLATFORMIO_OPTIONS)
-            if unknown:
-                warnings.add(
-                    "Ignore unknown `%s` options in section `[platformio]`" %
-                    ", ".join(unknown))
+        return (self._validate_platformio_options()
+                and self._validate_env_options())
+
+    def _validate_platformio_options(self):
+        if not self._parser.has_section("platformio"):
+            return True
+        warnings = set()
+
+        # legacy `lib_extra_dirs`
+        if self._parser.has_option("platformio", "lib_extra_dirs"):
+            if not self._parser.has_section("env"):
+                self._parser.add_section("env")
+            self._parser.set("env", "lib_extra_dirs",
+                             self._parser.get("platformio", "lib_extra_dirs"))
+            self._parser.remove_option("platformio", "lib_extra_dirs")
+            warnings.add(
+                "`lib_extra_dirs` option is deprecated in section "
+                "`platformio`! Please move it to global `env` section")
+
+        unknown = set(k for k, _ in self.items("platformio")) - set(
+            KNOWN_PLATFORMIO_OPTIONS)
+        if unknown:
+            warnings.add(
+                "Ignore unknown `%s` options in section `[platformio]`" %
+                ", ".join(unknown))
+
+        for warning in warnings:
+            click.secho("Warning! %s" % warning, fg="yellow")
+
+        return True
+
+    def _validate_env_options(self):
+        warnings = set()
 
-        # check [env:*] sections
         for section in self._parser.sections():
             if section != "env" and not section.startswith("env:"):
                 continue