diff --git a/indra/newview/llappviewer.cpp b/indra/newview/llappviewer.cpp
index 2d4838814e32f2c28566f5f3935bd17ac165ad8d..e74a7a84c383562fa726f858c2aa272113d3eecc 100644
--- a/indra/newview/llappviewer.cpp
+++ b/indra/newview/llappviewer.cpp
@@ -897,6 +897,18 @@ bool LLAppViewer::init()
 		return 0;
 	}
 
+	// Without SSE2 support we will crash almost immediately, warn here.
+	if (!gSysCPU.hasSSE2())
+	{	
+		// can't use an alert here since we're exiting and
+		// all hell breaks lose.
+		OSMessageBox(
+			LLNotifications::instance().getGlobalString("UnsupportedCPUSSE2"),
+			LLStringUtil::null,
+			OSMB_OK);
+		return 0;
+	}
+
 	// alert the user if they are using unsupported hardware
 	if(!gSavedSettings.getBOOL("AlertedUnsupportedHardware"))
 	{
diff --git a/indra/newview/skins/default/xui/en/notifications.xml b/indra/newview/skins/default/xui/en/notifications.xml
index 4fbe7b564f247f5ddd1434fb1318ccce0811028b..de133790991d6b6d9d8a70882498b4ee4ce124bb 100644
--- a/indra/newview/skins/default/xui/en/notifications.xml
+++ b/indra/newview/skins/default/xui/en/notifications.xml
@@ -6737,6 +6737,12 @@ The site at '<nolink>[HOST_NAME]</nolink>' in realm '
 - Your CPU speed does not meet the minimum requirements.
   </global>
 
+  <global name="UnsupportedCPUSSE2">
+Your CPU does not seem to have the required support for SSE2 operations.
+
+Please see http://www.secondlife.com/corporate/sysreqs.php for information about system requirements.
+  </global>
+
   <global name="UnsupportedGLRequirements">
 You do not appear to have the proper hardware requirements for [APP_NAME]. [APP_NAME] requires an OpenGL graphics card that has multitexture support. If this is the case, you may want to make sure that you have the latest drivers for your graphics card, and service packs and patches for your operating system.