diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 31daacd87..314e1079c 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -149,7 +149,43 @@ Build from source
 
 4. If a project has `project/build.properties` defined, either delete the file or change `sbt.version` to `0.13.10-SNAPSHOT`.
 
+## Diagnosing build failures
+
+Globally included plugins can interfere building `sbt`; if you are getting errors building sbt, try disabling all globally included plugins and try again.
+
+Running Tests
+=============
+
+sbt has an extensive test suite of Unit tests and Integration tests!
+
+Unit / Functional tests
+-----------------------
+
+Various functional and unit tests are defined throughout the
+project. To run all of them, run `sbt test`. You can run a single test
+suite with `sbt testOnly`
+
+Integration tests
+-----------------
+
+Scripted integration tests reside in `sbt/src/sbt-test` and are
+written using the same testing infrastructure sbt plugin authors can
+use to test their own plugins with sbt. You can read more about this
+style of tests [here](http://eed3si9n.com/testing-sbt-plugins).
+
+You can run the integration tests with the `sbt scripted` sbt
+command. To run a single test, such as the test in
+`sbt/src/sbt-test/project/global-plugin`, simply run:
+
+    sbt scripted project/global-plugin
+
+Please note that these tests run PAINFULLY slow if the version set in
+`build.sbt` is set to SNAPSHOT, as every time the scripted test boots
+up a test instance of sbt, remote mirrors are scanned for possible
+updates. It is recommended that you set the version suffix to
+`-devel`, as in `0.13.10-devel`.
+
 Building Documentation
-----------------------
+======================
 
 The scala-sbt.org site documentation is a separate project [website](https://github.com/sbt/website). Follow [the steps in the README](https://github.com/sbt/website#scala-sbtorg) to generate the documentation.
diff --git a/main/src/main/scala/sbt/Load.scala b/main/src/main/scala/sbt/Load.scala
index 9fa0c712e..398292e3d 100755
--- a/main/src/main/scala/sbt/Load.scala
+++ b/main/src/main/scala/sbt/Load.scala
@@ -91,7 +91,10 @@ object Load {
   def buildGlobalSettings(base: File, files: Seq[File], config: sbt.LoadBuildConfiguration): ClassLoader => Seq[Setting[_]] =
     {
       val eval = mkEval(data(config.globalPluginClasspath), base, defaultEvalOptions)
-      val imports = BuildUtil.baseImports ++ BuildUtil.importAllRoot(config.globalPluginNames)
+
+      val imports = BuildUtil.baseImports ++
+        config.detectedGlobalPlugins.imports
+
       loader => {
         val loaded = EvaluateConfigurations(eval, files, imports)(loader)
         // TODO - We have a potential leak of config-classes in the global directory right now.
@@ -718,10 +721,13 @@ object Load {
     loadedPlugins: sbt.LoadedPlugins,
     eval: () => Eval,
     memoSettings: mutable.Map[File, LoadedSbtFile]): DiscoveredProjects = {
+
     // Default sbt files to read, if needed
     lazy val defaultSbtFiles = configurationSources(projectBase)
+
     // Classloader of the build
     val loader = loadedPlugins.loader
+
     // How to load an individual file for use later.
     // TODO - We should import vals defined in other sbt files here, if we wish to
     // share.  For now, build.sbt files have their own unique namespace.
@@ -730,11 +736,13 @@ object Load {
     // How to merge SbtFiles we read into one thing
     def merge(ls: Seq[LoadedSbtFile]): LoadedSbtFile = (LoadedSbtFile.empty /: ls) { _ merge _ }
     // Loads a given file, or pulls from the cache.
+
     def memoLoadSettingsFile(src: File): LoadedSbtFile = memoSettings.getOrElse(src, {
       val lf = loadSettingsFile(src)
       memoSettings.put(src, lf.clearProjects) // don't load projects twice
       lf
     })
+
     // Loads a set of sbt files, sorted by their lexical name (current behavior of sbt).
     def loadFiles(fs: Seq[File]): LoadedSbtFile =
       merge(fs.sortBy(_.getName).map(memoLoadSettingsFile))
@@ -971,6 +979,19 @@ final case class LoadBuildConfiguration(
     log: Logger) {
   lazy val (globalPluginClasspath, globalPluginLoader) = Load.pluginDefinitionLoader(this, Load.globalPluginClasspath(globalPlugin))
   lazy val globalPluginNames = if (globalPluginClasspath.isEmpty) Nil else Load.getPluginNames(globalPluginClasspath, globalPluginLoader)
+
+  private[sbt] lazy val globalPluginDefs = {
+    val pluginData = globalPlugin match {
+      case Some(x) => PluginData(x.data.fullClasspath, x.data.internalClasspath, Some(x.data.resolvers), Some(x.data.updateReport), Nil)
+      case None    => PluginData(globalPluginClasspath, Nil, None, None, Nil)
+    }
+    val baseDir = globalPlugin match {
+      case Some(x) => x.base
+      case _       => stagingDirectory
+    }
+    Load.loadPluginDefinition(baseDir, this, pluginData)
+  }
+  lazy val detectedGlobalPlugins = globalPluginDefs.detected
 }
 
 final class IncompatiblePluginsException(msg: String, cause: Throwable) extends Exception(msg, cause)
diff --git a/notes/0.13.10.markdown b/notes/0.13.10.markdown
index 76830707f..8e19fa621 100644
--- a/notes/0.13.10.markdown
+++ b/notes/0.13.10.markdown
@@ -11,6 +11,7 @@
   [@fkorotkov]: http://github.com/fkorotkov
   [@hgiddens]: https://github.com/hgiddens
   [@DavidPerezIngeniero]: https://github.com/DavidPerezIngeniero
+  [@timcharper]: https://github.com/timcharper
   [2302]: https://github.com/sbt/sbt/issues/2302
   [2303]: https://github.com/sbt/sbt/pull/2303
   [1967]: https://github.com/sbt/sbt/issues/1967
@@ -62,6 +63,8 @@
   [1968]: https://github.com/sbt/sbt/issues/1968
   [2264]: https://github.com/sbt/sbt/issues/2264
   [2172]: https://github.com/sbt/sbt/pull/2172
+  [2120]: https://github.com/sbt/sbt/issues/2120
+  [2399]: https://github.com/sbt/sbt/pull/2399
 
 ### Fixes with compatibility implications
 
@@ -109,6 +112,7 @@
 - Fixes `JavaErrorParser` to parse non-compile-errors [#2256][2256]/[#2272][2272] by [@Duhemm][@Duhemm]
 
 - Fixes task scheduling performance on large builds by skipping checks in `sbt.Execute`. [#2302][2302]/[#2303][2303] by [@jrudolph][@jrudolph]
+- Fixes autoImports for AutoPlugins for global configuration files. [#2120][2120]/[#2399][2399] by [@timcharper][@timcharper]
 
 ### Def.settings
 
diff --git a/sbt/src/sbt-test/project/global-plugin/global/plugins/A.scala b/sbt/src/sbt-test/project/global-plugin/global/plugins/A.scala
index b75a623b5..bbf9fc243 100644
--- a/sbt/src/sbt-test/project/global-plugin/global/plugins/A.scala
+++ b/sbt/src/sbt-test/project/global-plugin/global/plugins/A.scala
@@ -1,5 +1,15 @@
 package test
 
+import sbt._
+
 object Global {
   val x = 3
 }
+
+object GlobalAutoPlugin extends AutoPlugin {
+
+  object autoImport {
+    lazy val globalAutoPluginSetting = settingKey[String]("A top level setting declared in a plugin.")
+  }
+
+}
diff --git a/sbt/src/sbt-test/project/global-plugin/global/plugins/B.scala b/sbt/src/sbt-test/project/global-plugin/global/plugins/B.scala
new file mode 100644
index 000000000..9d28ecc84
--- /dev/null
+++ b/sbt/src/sbt-test/project/global-plugin/global/plugins/B.scala
@@ -0,0 +1,7 @@
+import sbt._
+
+object GlobalLegacyPlugin extends sbt.Plugin {
+  import sbt.Keys._
+  val globalLegacyPluginSetting = SettingKey[String]("A top level setting declared by a legacy plugin")
+  val useGlobalLegacyPluginSetting = globalLegacyPluginSetting in Global
+}
diff --git a/sbt/src/sbt-test/project/global-plugin/global/useGlobalAutoPlugin.sbt b/sbt/src/sbt-test/project/global-plugin/global/useGlobalAutoPlugin.sbt
new file mode 100644
index 000000000..db85875ab
--- /dev/null
+++ b/sbt/src/sbt-test/project/global-plugin/global/useGlobalAutoPlugin.sbt
@@ -0,0 +1,2 @@
+// If the GlobalAutoPlugin.autoImport._ does not get brought in, this will fail:
+globalAutoPluginSetting := "bar"
diff --git a/sbt/src/sbt-test/project/global-plugin/global/useGlobalLegacyPlugin.sbt b/sbt/src/sbt-test/project/global-plugin/global/useGlobalLegacyPlugin.sbt
new file mode 100644
index 000000000..d17e24a85
--- /dev/null
+++ b/sbt/src/sbt-test/project/global-plugin/global/useGlobalLegacyPlugin.sbt
@@ -0,0 +1,5 @@
+/*
+ If the GlobalLegacyPlugin 'in' statements do not register and get
+ brought in to the global scope, this will fail
+ */
+globalLegacyPluginSetting := "foo"