diff --git a/compiler/main/DynFlags.hs b/compiler/main/DynFlags.hs
index 5425ace05bacf98579622091876d7474b65d358f..dbf5ff9f362fa8a10810555f929cfd3573a392c4 100644
--- a/compiler/main/DynFlags.hs
+++ b/compiler/main/DynFlags.hs
@@ -152,6 +152,7 @@ data DynFlag
    | Opt_D_dump_view_pattern_commoning
    | Opt_D_faststring_stats
    | Opt_DumpToFile			-- ^ Append dump output to files instead of stdout.
+   | Opt_D_no_debug_output
    | Opt_DoCoreLinting
    | Opt_DoStgLinting
    | Opt_DoCmmLinting
diff --git a/compiler/main/StaticFlags.hs b/compiler/main/StaticFlags.hs
index 538fe33a98769f4eb470d2b4409376e8bbbcad2d..6fa6032bb05be8cc949038a50b88f9b9561f098e 100644
--- a/compiler/main/StaticFlags.hs
+++ b/compiler/main/StaticFlags.hs
@@ -21,6 +21,7 @@ module StaticFlags (
 	opt_PprUserLength,
 	opt_SuppressUniques,
 	opt_PprStyle_Debug,
+        opt_NoDebugOutput,
 
 	-- profiling opts
 	opt_AutoSccsOnAllToplevs,
@@ -166,6 +167,7 @@ static_flags = [
   ,  ( "dsuppress-uniques", PassFlag addOpt )
   ,  ( "dppr-user-length",  AnySuffix addOpt )
   ,  ( "dopt-fuel",         AnySuffix addOpt )
+  ,  ( "dno-debug-output",  PassFlag addOpt )
       -- rest of the debugging flags are dynamic
 
 	--------- Profiling --------------------------------------------------
@@ -289,6 +291,9 @@ opt_PprUserLength   :: Int
 opt_PprUserLength	        = lookup_def_int "-dppr-user-length" 5 --ToDo: give this a name
 opt_Fuel            :: Int
 opt_Fuel                        = lookup_def_int "-dopt-fuel" maxBound
+opt_NoDebugOutput   :: Bool
+opt_NoDebugOutput               = lookUp  (fsLit "-dno-debug-output")
+
 
 -- profiling opts
 opt_AutoSccsOnAllToplevs :: Bool
diff --git a/compiler/utils/Outputable.lhs b/compiler/utils/Outputable.lhs
index b5d451ad642320aa94e6100e8733bb029ee925f1..61ad4ddd22216a6465956639cb539d2f66480260 100644
--- a/compiler/utils/Outputable.lhs
+++ b/compiler/utils/Outputable.lhs
@@ -53,7 +53,7 @@ module Outputable (
 import {-# SOURCE #-} 	Module( Module, ModuleName, moduleName )
 import {-# SOURCE #-} 	OccName( OccName )
 
-import StaticFlags	( opt_PprStyle_Debug, opt_PprUserLength )
+import StaticFlags
 import FastString
 import FastTypes
 import qualified Pretty
@@ -622,7 +622,9 @@ pprPanic    = pprAndThen panic		-- Throw an exn saying "bug in GHC"
 
 pprPgmError = pprAndThen pgmError	-- Throw an exn saying "bug in pgm being compiled"
 					--	(used for unusual pgm errors)
-pprTrace    = pprAndThen trace
+pprTrace str doc x
+   | opt_NoDebugOutput = x
+   | otherwise         = pprAndThen trace str doc x
 
 pprPanicFastInt :: String -> SDoc -> FastInt
 pprPanicFastInt heading pretty_msg = panicFastInt (show (doc PprDebug))
@@ -644,6 +646,7 @@ assertPprPanic file line msg
 		    msg]
 
 warnPprTrace :: Bool -> String -> Int -> SDoc -> a -> a
+warnPprTrace _     _file _line _msg x | opt_NoDebugOutput = x
 warnPprTrace False _file _line _msg x = x
 warnPprTrace True   file  line  msg x
   = trace (show (doc PprDebug)) x
diff --git a/docs/users_guide/debugging.xml b/docs/users_guide/debugging.xml
index 638ab7a4b50d732352fa82a0db4caefe7100a8d1..e00cd8fa4e028e5bd24860cabbd764a5205fe2e3 100644
--- a/docs/users_guide/debugging.xml
+++ b/docs/users_guide/debugging.xml
@@ -435,14 +435,18 @@
       </varlistentry>
 
       <varlistentry>
-	<term>
-          <option>-dshow-unused-imports</option>
-          <indexterm><primary><option>-dshow-unused-imports</option></primary></indexterm>
+        <term>
+          <option>-dno-debug-output</option>
+          <indexterm><primary><option>-dno-debug-output</option></primary></indexterm>
         </term>
-	<listitem>
-	  <para>Have the renamer report what imports does not
-	contribute.</para>
-	</listitem>
+        <listitem>
+          <para>Suppress any unsolicited debugging output.  When GHC
+            has been built with the <literal>DEBUG</literal> option it
+            occasionally emits debug output of interest to developers.
+            The extra output can confuse the testing framework and
+            cause bogus test failures, so this flag is provided to
+            turn it off.</para>
+        </listitem>
       </varlistentry>
     </variablelist>
   </sect2>
diff --git a/docs/users_guide/flags.xml b/docs/users_guide/flags.xml
index 7de1ae8e86a3d822bf980af182eacfcf50fe0239..9b1e272d9b257a8543539fce5356b67ae4b6e971 100644
--- a/docs/users_guide/flags.xml
+++ b/docs/users_guide/flags.xml
@@ -2213,6 +2213,12 @@
 	      <entry>dynamic</entry>
 	      <entry>-</entry>
 	    </row>
+	    <row>
+	      <entry><option>-dno-debug-output</option></entry>
+	      <entry>Suppress unsolicited debugging output</entry>
+	      <entry>static</entry>
+	      <entry>-</entry>
+	    </row>
 	    <row>
 	      <entry><option>-dppr-debug</option></entry>
 	      <entry>Turn on debug printing (more verbose)</entry>