Index: lib/IR/Verifier.cpp
===================================================================
--- lib/IR/Verifier.cpp
+++ lib/IR/Verifier.cpp
@@ -3398,8 +3398,12 @@
   }
 
   const Use &U = I.getOperandUse(i);
-  Assert(InstsInThisBlock.count(Op) || DT.dominates(Op, U),
-         "Instruction does not dominate all uses!", Op, &I);
+  if (isa<PHINode>(I))
+    Assert(DT.dominates(Op, U),
+           "Instruction does not dominate PHI node's incoming edge!", Op, &I);
+  else
+    Assert(InstsInThisBlock.count(Op) || DT.dominates(Op, U),
+           "Instruction does not dominate all uses!", Op, &I);
 }
 
 void Verifier::visitDereferenceableMetadata(Instruction& I, MDNode* MD) {
Index: test/Transforms/LoopVectorize/phi-hang.ll
===================================================================
--- test/Transforms/LoopVectorize/phi-hang.ll
+++ test/Transforms/LoopVectorize/phi-hang.ll
@@ -1,33 +1,5 @@
 ; RUN: opt -S -loop-vectorize < %s
 
-; PR15384
-define void @test1(i32 %arg) {
-bb:
-  br label %bb1
-
-bb1:                                              ; preds = %bb5, %bb
-  %tmp = phi i32 [ 1, %bb ], [ %tmp7, %bb5 ]
-  %tmp2 = phi i32 [ %arg, %bb ], [ %tmp9, %bb5 ]
-  br i1 true, label %bb5, label %bb3
-
-bb3:                                              ; preds = %bb1
-  br label %bb4
-
-bb4:                                              ; preds = %bb3
-  br label %bb5
-
-bb5:                                              ; preds = %bb4, %bb1
-  %tmp6 = phi i32 [ 0, %bb4 ], [ %tmp, %bb1 ]
-  %tmp7 = phi i32 [ 0, %bb4 ], [ %tmp6, %bb1 ]
-  %tmp8 = phi i32 [ 0, %bb4 ], [ %tmp, %bb1 ]
-  %tmp9 = add nsw i32 %tmp2, 1
-  %tmp10 = icmp eq i32 %tmp9, 0
-  br i1 %tmp10, label %bb11, label %bb1
-
-bb11:                                             ; preds = %bb5
-  ret void
-}
-
 ; PR15748
 define void @test2() {
 bb:
Index: test/Verifier/dominates.ll
===================================================================
--- test/Verifier/dominates.ll
+++ test/Verifier/dominates.ll
@@ -20,7 +20,7 @@
   %y3 = landingpad i32
           cleanup
   ret void
-; CHECK: Instruction does not dominate all uses!
+; CHECK: Instruction does not dominate PHI node's incoming edge!
 ; CHECK-NEXT:  %y1 = invoke i32 @g()
 ; CHECK-NEXT:        to label %bb1 unwind label %bb2
 ; CHECK-NEXT:  %y2 = phi i32 [ %y1, %bb0 ]
@@ -38,7 +38,7 @@
 bb3:
   %y3 = phi i32 [%y1, %bb2]
   ret void
-; CHECK: Instruction does not dominate all uses!
+; CHECK: Instruction does not dominate PHI node's incoming edge!
 ; CHECK-NEXT:  %y1 = invoke i32 @g()
 ; CHECK-NEXT:          to label %bb1 unwind label %bb2
 ; CHECK-NEXT:  %y3 = phi i32 [ %y1, %bb2 ]
@@ -51,7 +51,20 @@
   %y3 = phi i32 [%y1, %bb0]
   %y1 = add i32 %x, 1
   ret void
-; CHECK: Instruction does not dominate all uses!
+; CHECK: Instruction does not dominate PHI node's incoming edge!
 ; CHECK-NEXT:  %y1 = add i32 %x, 1
 ; CHECK-NEXT:  %y3 = phi i32 [ %y1, %bb0 ]
 }
+
+define void @f5() {
+entry:
+  br label %next
+
+next:
+  %y = phi i32 [ 0, %entry ]
+  %x = phi i32 [ %y, %entry ]
+  ret void
+; CHECK: Instruction does not dominate PHI node's incoming edge!
+; CHECK-NEXT:  %y = phi i32 [ 0, %entry ]
+; CHECK-NEXT:  %x = phi i32 [ %y, %entry ]
+}