Index: lib/CodeGen/AsmPrinter/AsmPrinter.cpp
===================================================================
--- lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -1439,8 +1439,14 @@
 
     OutStreamer->EmitLabel(GetJTISymbol(JTI));
 
-    for (unsigned ii = 0, ee = JTBBs.size(); ii != ee; ++ii)
+    for (unsigned ii = 0, ee = JTBBs.size(); ii != ee; ++ii) {
+      // If a JTBB has a number of -1 it was pruned as unreachable during
+      // optimization.  It is not feasible to remove the BB from the JT
+      // table during pruning, so simply ignore unreachable JTBBs here.
+      if (JTBBs[ii]->getNumber() == -1)
+        continue;
       EmitJumpTableEntry(MJTI, JTBBs[ii], JTI);
+    }
   }
   if (!JTInDiffSection)
     OutStreamer->EmitDataRegion(MCDR_DataRegionEnd);