Index: lib/Transforms/Vectorize/LoopVectorize.cpp
===================================================================
--- lib/Transforms/Vectorize/LoopVectorize.cpp
+++ lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -450,10 +450,10 @@
   /// vectorizing this phi node.
   void fixReduction(PHINode *Phi);
 
-  /// \brief The Loop exit block may have single value PHI nodes where the
-  /// incoming value is 'Undef'. While vectorizing we only handled real values
-  /// that were defined inside the loop. Here we fix the 'undef case'.
-  /// See PR14725.
+  /// \brief The Loop exit block may have single value PHI nodes with some
+  /// incoming value. While vectorizing we only handled real values
+  /// that were defined inside the loop and we should have one value for
+  /// each predecessor of its parent basic block. See PR14725.
   void fixLCSSAPHIs();
 
   /// Iteratively sink the scalarized operands of a predicated instruction into
@@ -4346,7 +4346,7 @@
     if (!LCSSAPhi)
       break;
     if (LCSSAPhi->getNumIncomingValues() == 1)
-      LCSSAPhi->addIncoming(UndefValue::get(LCSSAPhi->getType()),
+        LCSSAPhi->addIncoming(LCSSAPhi->getIncomingValue(0),
                             LoopMiddleBlock);
   }
 }
Index: test/Transforms/LoopVectorize/pr32859.ll
===================================================================
--- /dev/null
+++ test/Transforms/LoopVectorize/pr32859.ll
@@ -0,0 +1,30 @@
+; RUN: opt < %s -loop-vectorize -S 2>&1 | FileCheck %s
+
+; CHECK-LABEL: for.cond.preheader:
+; CHECK: %e.0.ph = phi i32 [ 0, %if.end.2.i ], [ 0, %middle.block ]
+
+; Function Attrs: nounwind uwtable
+define void @main() #0 {
+entry:
+  br label %for.cond1.preheader.i
+
+for.cond1.preheader.i:                            ; preds = %if.end.2.i, %entry
+  %c.06.i = phi i32 [ 0, %entry ], [ %inc5.i, %if.end.2.i ]
+  %tobool.i = icmp ne i32 undef, 0
+  br label %if.end.2.i
+
+if.end.2.i:                                       ; preds = %for.cond1.preheader.i
+  %inc5.i = add nsw i32 %c.06.i, 1
+  %cmp.i = icmp slt i32 %inc5.i, 16
+  br i1 %cmp.i, label %for.cond1.preheader.i, label %for.cond.preheader
+
+for.cond.preheader:                               ; preds = %if.end.2.i
+  %e.0.ph = phi i32 [ 0, %if.end.2.i ]
+  unreachable
+}
+
+attributes #0 = { nounwind uwtable "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+fxsr,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
+
+!llvm.ident = !{!0}
+
+!0 = !{!"clang version 5.0.0 (http://llvm.org/git/clang.git 08c94e4bd75c5a2e4de5ea108d98739f5179dbeb) (http://llvm.org/git/llvm.git 7d66f52694bdfabf0081a1d40b99fca0c189a988)"}