diff --git a/src/jdk.compiler/share/classes/com/sun/tools/sjavac/client/SjavacClient.java b/src/jdk.compiler/share/classes/com/sun/tools/sjavac/client/SjavacClient.java
index <HASH>..<HASH> 100644
--- a/src/jdk.compiler/share/classes/com/sun/tools/sjavac/client/SjavacClient.java
+++ b/src/jdk.compiler/share/classes/com/sun/tools/sjavac/client/SjavacClient.java
@@ -139,7 +139,11 @@ public class SjavacClient implements Sjavac {
                 String content = typeAndContent[1];
 
                 try {
-                    Log.log(Log.Level.valueOf(type), "[server] " + content);
+                    if (Log.isDebugging()) {
+                        // Distinguish server generated output if debugging.
+                        content = "[sjavac-server] " + content;
+                    }
+                    Log.log(Log.Level.valueOf(type), content);
                     continue;
                 } catch (IllegalArgumentException e) {
                     // Parsing of 'type' as log level failed.
<I>: Sjavac should not prefix server generated log messages with [server]
Summary: Dropped the [server] prefix unless debug output is enabled.
Reviewed-by: jjg