diff --git a/main/src/main/scala/sbt/Main.scala b/main/src/main/scala/sbt/Main.scala
index a1a54f095..3447ce8ba 100644
--- a/main/src/main/scala/sbt/Main.scala
+++ b/main/src/main/scala/sbt/Main.scala
@@ -9,7 +9,7 @@ package sbt
 
 import java.io.{ File, IOException }
 import java.net.URI
-import java.util.concurrent.{ Executors, ForkJoinPool }
+import java.util.concurrent.ForkJoinPool
 import java.util.concurrent.atomic.AtomicBoolean
 import java.util.{ Locale, Properties }
 
diff --git a/main/src/main/scala/sbt/MainLoop.scala b/main/src/main/scala/sbt/MainLoop.scala
index 8b8c1763b..8e9558a1b 100644
--- a/main/src/main/scala/sbt/MainLoop.scala
+++ b/main/src/main/scala/sbt/MainLoop.scala
@@ -177,21 +177,14 @@ object MainLoop {
     }
 
   /** This is the main function State transfer function of the sbt command processing. */
-  def processCommand(exec: Exec, state: State): State =
-    processCommand(exec, state, () => Command.process(exec.commandLine, state))
-
-  private[sbt] def processCommand(
-      exec: Exec,
-      state: State,
-      runCommand: () => State
-  ): State = {
+  def processCommand(exec: Exec, state: State): State = {
     val channelName = exec.source map (_.channelName)
     StandardMain.exchange publishEventMessage
       ExecStatusEvent("Processing", channelName, exec.execId, Vector())
 
     try {
       def process(): State = {
-        val newState = runCommand()
+        val newState = Command.process(exec.commandLine, state)
         val doneEvent = ExecStatusEvent(
           "Done",
           channelName,
diff --git a/main/src/main/scala/sbt/internal/Continuous.scala b/main/src/main/scala/sbt/internal/Continuous.scala
index d87b7d710..a87060d34 100644
--- a/main/src/main/scala/sbt/internal/Continuous.scala
+++ b/main/src/main/scala/sbt/internal/Continuous.scala
@@ -188,7 +188,7 @@ private[sbt] object Continuous extends DeprecatedContinuous {
     inputs.foreach(i => repository.register(i.glob))
     val watchSettings = new WatchSettings(scopedKey)
     new Config(
-      scopedKey,
+      scopedKey.show,
       () => dynamicInputs.toSeq.sorted,
       watchSettings
     )
@@ -212,7 +212,7 @@ private[sbt] object Continuous extends DeprecatedContinuous {
     val onFail = Command.command(failureCommandName)(identity)
     // This adds the "SbtContinuousWatchOnFail" onFailure handler which allows us to determine
     // whether or not the last task successfully ran. It is used in the makeTask method below.
-    val s = (FailureWall :: state).copy(
+    val s = state.copy(
       onFailure = Some(Exec(failureCommandName, None)),
       definedCommands = state.definedCommands :+ onFail
     )
@@ -226,22 +226,29 @@ private[sbt] object Continuous extends DeprecatedContinuous {
      * if they are not visible in the input graph due to the use of Def.taskDyn.
      */
     def makeTask(cmd: String): (String, State, () => Boolean) = {
-      val newState = s.put(DynamicInputs, mutable.Set.empty[DynamicInput])
-      val task = Parser
-        .parse(cmd, Command.combine(newState.definedCommands)(newState))
-        .getOrElse(
-          throw new IllegalStateException(
-            "No longer able to parse command after transforming state"
-          )
-        )
+      val newState = s
+        .put(DynamicInputs, mutable.Set.empty[DynamicInput])
+        .copy(remainingCommands = Exec(cmd, None, None) :: Exec(FailureWall, None, None) :: Nil)
       (
         cmd,
         newState,
         () => {
-          MainLoop
-            .processCommand(Exec(cmd, None), newState, task)
-            .remainingCommands
-            .forall(_.commandLine != failureCommandName)
+          @tailrec
+          def impl(s: State): Boolean = {
+            s.remainingCommands match {
+              case exec :: rest =>
+                val updatedState = MainLoop.processCommand(exec, s.copy(remainingCommands = rest))
+                val remaining =
+                  updatedState.remainingCommands.takeWhile(_.commandLine != FailureWall)
+                remaining match {
+                  case Nil =>
+                    updatedState.remainingCommands.forall(_.commandLine != failureCommandName)
+                  case _ => impl(updatedState)
+                }
+              case Nil => true
+            }
+          }
+          impl(newState)
         }
       )
     }
@@ -256,7 +263,7 @@ private[sbt] object Continuous extends DeprecatedContinuous {
 
     // Convert the command strings to runnable tasks, which are represented by
     // () => Try[Boolean].
-    val taskParser = Command.combine(s.definedCommands)(s)
+    val taskParser = s.combinedParser
     // This specified either the task corresponding to a command or the command itself if the
     // the command cannot be converted to a task.
     val (invalid, valid) =
@@ -378,6 +385,9 @@ private[sbt] object Continuous extends DeprecatedContinuous {
     } finally repo.close()
   }
 
+  // This is defined so we can assign a task key to a command to parse the WatchSettings.
+  private[this] val globalWatchSettingKey =
+    taskKey[Unit]("Internal task key. Not actually used.").withRank(KeyRanks.Invisible)
   private def parseCommand(command: String, state: State): Seq[ScopedKey[_]] = {
     // Collect all of the scoped keys that are used to delegate the multi commands. These are
     // necessary to extract all of the transitive globs that we need to monitor during watch.
@@ -391,9 +401,13 @@ private[sbt] object Continuous extends DeprecatedContinuous {
           val aliases = BasicCommands.allAliases(state)
           aliases.collectFirst { case (`command`, aliased) => aliased } match {
             case Some(aliased) => impl(aliased)
-            case _ =>
-              val msg = s"Error attempting to extract scope from $command: $e."
-              throw new IllegalStateException(msg)
+            case None =>
+              Parser.parse(command, state.combinedParser) match {
+                case Right(_) => globalWatchSettingKey.scopedKey :: Nil
+                case _ =>
+                  val msg = s"Error attempting to extract scope from $command: $e."
+                  throw new IllegalStateException(msg)
+              }
           }
         case _ => Nil: Seq[ScopedKey[_]]
       }
@@ -619,7 +633,7 @@ private[sbt] object Continuous extends DeprecatedContinuous {
         configs.map { config =>
           // Create a logger with a scoped key prefix so that we can tell from which task there
           // were inputs that matched the event path.
-          val configLogger = logger.withPrefix(config.key.show)
+          val configLogger = logger.withPrefix(config.command)
           observers.addObserver { e =>
             if (config.inputs().exists(_.glob.matches(e.path))) {
               configLogger.debug(s"Accepted event for ${e.path}")
@@ -910,12 +924,12 @@ private[sbt] object Continuous extends DeprecatedContinuous {
    * Container class for all of the components we need to setup a watch for a particular task or
    * input task.
    *
-   * @param key           the [[ScopedKey]] instance for the task we will watch
+   * @param command       the name of the command/task to run with each iteration
    * @param inputs        the transitive task inputs (see [[SettingsGraph]])
    * @param watchSettings the [[WatchSettings]] instance for the task
    */
   private final class Config private[internal] (
-      val key: ScopedKey[_],
+      val command: String,
       val inputs: () => Seq[DynamicInput],
       val watchSettings: WatchSettings
   ) {
diff --git a/sbt/src/sbt-test/watch/commands/build.sbt b/sbt/src/sbt-test/watch/commands/build.sbt
new file mode 100644
index 000000000..bf3d80a7c
--- /dev/null
+++ b/sbt/src/sbt-test/watch/commands/build.sbt
@@ -0,0 +1,56 @@
+import java.nio.file.Files
+
+import scala.collection.JavaConverters._
+
+val foo = taskKey[Unit]("foo")
+foo := {
+  val fooTxt = baseDirectory.value / "foo.txt"
+  val _ = println(s"foo inputs: ${(foo / allInputFiles).value}")
+  IO.write(fooTxt, "foo")
+  println(s"foo wrote to $foo")
+}
+foo / fileInputs += baseDirectory.value.toGlob / "foo.txt"
+
+Global / watchTriggers += baseDirectory.value.toGlob / "bar.txt"
+
+commands ++= Seq(
+  Command.command("eval-foo") { s =>
+    Project.extract(s).runTask(foo, s)
+    s
+  },
+  Command.command("write-bar") { s =>
+    val bar = Project.extract(s).get(baseDirectory) / "bar.txt"
+    IO.write(bar, "bar")
+    println(s"write-bar wrote to $bar")
+    s
+  }
+)
+
+watchOnFileInputEvent := { (_, _) => sbt.nio.Watch.CancelWatch }
+
+/*
+ * This test ensures that when watching a cross build that commands are run for multiple scala
+ * versions. It also checks that the fileInputs are automatically detected during task evaluation
+ * even though we can't directly inspect the fileInputs of the cross ('+') command.
+ */
+val expectFailure = taskKey[Unit]("expect failure")
+expectFailure := {
+  val main = baseDirectory.value.toPath / "src" / "main"
+  val crossDir = main / (if (scalaVersion.value.startsWith("2.11")) "scala-2.11" else "scala-2.12")
+  (Compile / compile).result.value.toEither match {
+    case Left(_) =>
+      Files.write(crossDir / "Foo.scala", "class Foo".getBytes)
+      throw new IllegalStateException("Compilation failed.")
+    case Right(_) =>
+      if (!Files.walk(main).iterator.asScala.exists(_.getFileName.toString == "first.scala"))
+        Files.write(crossDir / "first.scala", "class first".getBytes)
+      else Files.write(crossDir / "second.scala", "class second".getBytes)
+  }
+}
+expectFailure / watchOnFileInputEvent := { (_, e) =>
+  if (e.path.getFileName.toString == "second.scala") sbt.nio.Watch.CancelWatch
+  else sbt.nio.Watch.Trigger
+}
+
+
+crossScalaVersions := Seq("2.11.12", "2.12.8")
diff --git a/sbt/src/sbt-test/watch/commands/src/main/scala-2.11/Foo.scala b/sbt/src/sbt-test/watch/commands/src/main/scala-2.11/Foo.scala
new file mode 100644
index 000000000..cc04bc468
--- /dev/null
+++ b/sbt/src/sbt-test/watch/commands/src/main/scala-2.11/Foo.scala
@@ -0,0 +1 @@
+class Foo {
\ No newline at end of file
diff --git a/sbt/src/sbt-test/watch/commands/src/main/scala-2.12/Foo.scala b/sbt/src/sbt-test/watch/commands/src/main/scala-2.12/Foo.scala
new file mode 100644
index 000000000..cc04bc468
--- /dev/null
+++ b/sbt/src/sbt-test/watch/commands/src/main/scala-2.12/Foo.scala
@@ -0,0 +1 @@
+class Foo {
\ No newline at end of file
diff --git a/sbt/src/sbt-test/watch/commands/src/main/scala/Bar.scala b/sbt/src/sbt-test/watch/commands/src/main/scala/Bar.scala
new file mode 100644
index 000000000..4a643c4dd
--- /dev/null
+++ b/sbt/src/sbt-test/watch/commands/src/main/scala/Bar.scala
@@ -0,0 +1 @@
+class Bar
\ No newline at end of file
diff --git a/sbt/src/sbt-test/watch/commands/test b/sbt/src/sbt-test/watch/commands/test
new file mode 100644
index 000000000..2eeb6d22c
--- /dev/null
+++ b/sbt/src/sbt-test/watch/commands/test
@@ -0,0 +1,6 @@
+> ~ eval-foo
+
+> ~ write-bar
+
+> set watchOnFileInputEvent := (expectFailure / watchOnFileInputEvent).value
+> ~ +expectFailure
diff --git a/sbt/src/sbt-test/watch/on-change/build.sbt b/sbt/src/sbt-test/watch/on-change/build.sbt
index b1ccae48d..048ca05aa 100644
--- a/sbt/src/sbt-test/watch/on-change/build.sbt
+++ b/sbt/src/sbt-test/watch/on-change/build.sbt
@@ -1,8 +1,10 @@
 import java.nio.file._
+import java.nio.file.attribute.FileTime
+
 import sbt.nio.Keys._
 import sbt.nio._
+
 import scala.concurrent.duration._
-import StandardCopyOption.{ REPLACE_EXISTING => replace }
 
 watchTriggeredMessage := { (i, path: Path, c) =>
   val prev = watchTriggeredMessage.value
@@ -16,14 +18,15 @@ watchOnIteration := { i: Int =>
   val src =
     base.resolve("src").resolve("main").resolve("scala").resolve("sbt").resolve("test")
   val changes = base.resolve("changes")
-  Files.copy(changes.resolve("C.scala"), src.resolve("C.scala"), replace)
-  if (i < 5) {
+  def copy(fileName: String): Unit = {
     val content =
-      new String(Files.readAllBytes(changes.resolve("A.scala"))) + "\n" + ("//" * i)
-    Files.write(src.resolve("A.scala"), content.getBytes)
-  } else {
-    Files.copy(changes.resolve("B.scala"), src.resolve("B.scala"), replace)
+      new String(Files.readAllBytes(changes.resolve(fileName))) + "\n" + ("//" * i)
+    Files.write(src.resolve(fileName), content.getBytes)
   }
+  val c = src.resolve("C.scala")
+  Files.setLastModifiedTime(c, FileTime.fromMillis(Files.getLastModifiedTime(c).toMillis + 1111))
+  if (i < 5) copy("A.scala")
+  else copy("B.scala")
   println(s"Waiting for changes...")
   Watch.Ignore
 }
diff --git a/scripted-sbt-redux/src/main/scala/sbt/scriptedtest/ScriptedTests.scala b/scripted-sbt-redux/src/main/scala/sbt/scriptedtest/ScriptedTests.scala
index 5fef5fad7..03d871e56 100644
--- a/scripted-sbt-redux/src/main/scala/sbt/scriptedtest/ScriptedTests.scala
+++ b/scripted-sbt-redux/src/main/scala/sbt/scriptedtest/ScriptedTests.scala
@@ -232,7 +232,9 @@ final class ScriptedTests(
       case "source-dependencies/linearization"           => LauncherBased // sbt/Package$
       case "source-dependencies/named"                   => LauncherBased // sbt/Package$
       case "source-dependencies/specialized"             => LauncherBased // sbt/Package$
-      case "watch/managed"                               => LauncherBased // sbt/Package$
+      case "watch/commands" =>
+        LauncherBased // java.lang.ClassNotFoundException: javax.tools.DiagnosticListener when run with java 11 and an old sbt launcher
+      case "watch/managed" => LauncherBased // sbt/Package$
       case "tests/test-cross" =>
         LauncherBased // the sbt metabuild classpath leaks into the test interface classloader in older versions of sbt
       case _ => RunFromSourceBased