diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index 027fe0656be5..76936d52c992 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -950,6 +950,9 @@ bool LoopVectorizationLegality::canVectorizeBlock(BasicBlock &BB) {
         DEBUG(dbgs() << "LV: Found an Mult reduction PHI."<< *Phi <<"\n");
         continue;
       }
+
+      DEBUG(dbgs() << "LV: Found an unidentified PHI."<< *Phi <<"\n");
+      return false;
     }// end of PHI handling
 
     // We still don't handle functions.
diff --git a/llvm/test/Transforms/LoopVectorize/2012-10-20-infloop.ll b/llvm/test/Transforms/LoopVectorize/2012-10-20-infloop.ll
index 16a77291995d..5caaffc8ddea 100644
--- a/llvm/test/Transforms/LoopVectorize/2012-10-20-infloop.ll
+++ b/llvm/test/Transforms/LoopVectorize/2012-10-20-infloop.ll
@@ -10,3 +10,18 @@ for.body:
  br label %for.body
 }
 
+
+
+define void @test2() nounwind {
+entry:
+ br label %for.body
+
+for.body:                                         ; preds = %for.body, %entry
+ %indvars.iv47 = phi i64 [ 0, %entry ], [ %indvars.iv.next48, %for.body ]
+ %0 = phi i32 [ 1, %entry ], [ 0, %for.body ]
+ %indvars.iv.next48 = add i64 %indvars.iv47, 1
+ br i1 undef, label %for.end, label %for.body
+
+for.end:                                          ; preds = %for.body
+ unreachable
+}