diff --git a/indra/newview/fslslpreproc.cpp b/indra/newview/fslslpreproc.cpp
index b2e815df0a..12f46fa2eb 100644
--- a/indra/newview/fslslpreproc.cpp
+++ b/indra/newview/fslslpreproc.cpp
@@ -1540,6 +1540,22 @@ void FSLSLPreprocessor::start_process()
 				}
 			}
 		}
+		else
+		{
+			// FIRE-31718: Preprocessor crashes viewer on recursive #include
+
+			// Truncate the resulting preprocessed script to something the text field can handle without
+			// freezing for so long the viewer disconnects. The usual script source code limit is 64kB so
+			// let's play it safe and allow twice as much here. The script is most likely already unusable
+			// at this point due to the preprocessor bailing out with an error earlier, so a truncated
+			// version doesn't hurt more than it already did.
+			if (output.size() > 128 * 1024)
+			{
+				output.resize(128 * 1024);
+				display_error(LLTrans::getString("fs_preprocessor_truncated"));
+			}
+		}
+
 		if (!errored)
 		{
 			if (preprocessor_enabled && use_compression)
diff --git a/indra/newview/skins/default/xui/en/strings.xml b/indra/newview/skins/default/xui/en/strings.xml
index 722bc66f90..4ecb7e2744 100644
--- a/indra/newview/skins/default/xui/en/strings.xml
+++ b/indra/newview/skins/default/xui/en/strings.xml
@@ -3153,6 +3153,7 @@ Your current position: [AVATAR_POS]
   <string name="fs_preprocessor_cache_completed">Caching completed for '[FILENAME]'</string>
   <string name="fs_preprocessor_cache_unsafe">Error: script named '[FILENAME]' isn't safe to copy to the filesystem. This include will fail.</string>
   <string name="fs_preprocessor_caching_err">Error caching included file '[FILENAME]'</string>
+  <string name="fs_preprocessor_truncated">Warning: Preprocessor output truncated due to excessive script text size. This script will most likely not work.</string>
   <!-- </FS:Cron> -->
 
   <!-- Animation Explorer -->