diff --git a/src/compiler/scala/tools/nsc/Global.scala b/src/compiler/scala/tools/nsc/Global.scala
index 230aae668d0a..c59003c9a242 100644
--- a/src/compiler/scala/tools/nsc/Global.scala
+++ b/src/compiler/scala/tools/nsc/Global.scala
@@ -1685,6 +1685,20 @@ class Global(var currentSettings: Settings, reporter0: LegacyReporter)
   }
 
   def createJavadoc    = false
+
+  var typerDepth: Int = 0
+  var maxTyperDepth = 0
+  final def decTyperDepth(): Unit = {
+    typerDepth -= 1
+  }
+  final def incTyperDepth(): Unit = {
+    typerDepth += 1
+    maxTyperDepth = math.max(typerDepth, maxTyperDepth)
+  }
+  val typerDepthReportThreshold: Int = Integer.getInteger("scala.typer.ast.depth.threshhold", Int.MaxValue)
+  scala.sys.addShutdownHook {
+    println("max typer depth: " + maxTyperDepth)
+  }
 }
 
 object Global {
diff --git a/src/compiler/scala/tools/nsc/typechecker/Namers.scala b/src/compiler/scala/tools/nsc/typechecker/Namers.scala
index ae7813a96bd8..af10a93ef75c 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Namers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Namers.scala
@@ -2015,8 +2015,12 @@ trait Namers extends MethodSynthesis {
 
     override def complete(sym: Symbol) = {
       lockedCount += 1
+      val saved = typerDepth
       try completeImpl(sym)
-      finally lockedCount -= 1
+      finally {
+        typerDepth = saved
+        lockedCount -= 1
+      }
     }
   }
 
diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
index b572d37d2c31..f50787317337 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Typers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
@@ -5633,6 +5633,13 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper
     }
 
     def typed(tree: Tree, mode: Mode, pt: Type): Tree = {
+      incTyperDepth()
+      if (typerDepth > typerDepthReportThreshold) {
+        var pos = context.enclMethod.owner.pos
+        if (pos == NoPosition)
+          pos = tree.pos
+        reporter.warning(pos, "AST depth within " + context.owner.enclMethod.pos + " exceeds " + typerDepthReportThreshold + " at " + globalPhase.name )
+      }
       lastTreeToTyper = tree
       val statsEnabled = StatisticsStatics.areSomeHotStatsEnabled() && statistics.areHotStatsLocallyEnabled
       val startByType = if (statsEnabled) statistics.pushTimer(byTypeStack, byTypeNanos(tree.getClass)) else null
@@ -5707,6 +5714,7 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper
       } finally {
         if (shouldPopTypingStack) typingStack.pop(tree)
         if (statsEnabled) statistics.popTimer(byTypeStack, startByType)
+        decTyperDepth()
       }
     }