diff --git a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
--- a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
+++ b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
@@ -4053,8 +4053,7 @@
         TreeEntry *OpTE = Op.second;
         if (!VisitedOps.insert(OpTE).second)
           continue;
-        if (!OpTE->ReuseShuffleIndices.empty() ||
-            (IgnoreReorder && OpTE == VectorizableTree.front().get()))
+        if (!OpTE->ReuseShuffleIndices.empty())
           continue;
         const auto &Order = [OpTE, &GathersToOrders]() -> const OrdersType & {
           if (OpTE->State == TreeEntry::NeedToGather)
@@ -4174,6 +4173,8 @@
                 TE->ReorderIndices.empty()) &&
                "Non-matching sizes of user/operand entries.");
         reorderOrder(TE->ReorderIndices, Mask);
+        if (IgnoreReorder && TE == VectorizableTree.front().get())
+          IgnoreReorder = false;
       }
       // For gathers just need to reorder its scalars.
       for (TreeEntry *Gather : GatherOps) {
@@ -7853,9 +7854,10 @@
   auto *VecTy = FixedVectorType::get(ScalarTy, E->Scalars.size());
   switch (ShuffleOrOp) {
     case Instruction::PHI: {
-      assert(
-          (E->ReorderIndices.empty() || E != VectorizableTree.front().get()) &&
-          "PHI reordering is free.");
+      assert((E->ReorderIndices.empty() ||
+              E != VectorizableTree.front().get() ||
+              !E->UserTreeIndices.empty()) &&
+             "PHI reordering is free.");
       auto *PH = cast<PHINode>(VL0);
       Builder.SetInsertPoint(PH->getParent()->getFirstNonPHI());
       Builder.SetCurrentDebugLocation(PH->getDebugLoc());
diff --git a/llvm/test/Transforms/SLPVectorizer/X86/reoder-phi-operand.ll b/llvm/test/Transforms/SLPVectorizer/X86/reoder-phi-operand.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/Transforms/SLPVectorizer/X86/reoder-phi-operand.ll
@@ -0,0 +1,41 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -S -slp-vectorizer -mtriple=x86_64-unknown-linux-gnu < %s | FileCheck %s
+
+define ptr @test() {
+; CHECK-LABEL: @test(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[GREEN_I:%.*]] = getelementptr inbounds float, ptr null, i32 6
+; CHECK-NEXT:    [[TMP0:%.*]] = load <2 x float>, ptr [[GREEN_I]], align 4
+; CHECK-NEXT:    [[TMP1:%.*]] = fpext <2 x float> [[TMP0]] to <2 x double>
+; CHECK-NEXT:    br label [[BODY:%.*]]
+; CHECK:       body:
+; CHECK-NEXT:    [[TMP2:%.*]] = phi <2 x double> [ [[TMP5:%.*]], [[BODY]] ], [ [[TMP1]], [[ENTRY:%.*]] ]
+; CHECK-NEXT:    [[TMP3:%.*]] = load <2 x i16>, ptr null, align 2
+; CHECK-NEXT:    [[TMP4:%.*]] = uitofp <2 x i16> [[TMP3]] to <2 x double>
+; CHECK-NEXT:    [[SHUFFLE:%.*]] = shufflevector <2 x double> [[TMP4]], <2 x double> poison, <2 x i32> <i32 1, i32 0>
+; CHECK-NEXT:    [[TMP5]] = call <2 x double> @llvm.fmuladd.v2f64(<2 x double> zeroinitializer, <2 x double> [[SHUFFLE]], <2 x double> [[TMP2]])
+; CHECK-NEXT:    br label [[BODY]]
+;
+entry:
+  %green.i = getelementptr inbounds float, ptr null, i32 6
+  %blue.i = getelementptr inbounds float, ptr null, i32 7
+  %0 = load float, ptr %green.i, align 4
+  %conv197 = fpext float %0 to double
+  %1 = load float, ptr %blue.i, align 8
+  %conv199 = fpext float %1 to double
+  br label %body
+
+body:
+  %phi1 = phi double [ %3, %body ], [ %conv197, %entry ]
+  %phi2 = phi double [ %5, %body ], [ %conv199, %entry ]
+  %green = getelementptr inbounds i16, ptr null, i32 1
+  %2 = load i16, ptr %green, align 2
+  %conv1 = uitofp i16 %2 to double
+  %3 = call double @llvm.fmuladd.f64(double 0.000000e+00, double %conv1, double %phi1)
+  %4 = load i16, ptr null, align 2
+  %conv2 = uitofp i16 %4 to double
+  %5 = call double @llvm.fmuladd.f64(double 0.000000e+00, double %conv2, double %phi2)
+  br label %body
+}
+
+declare double @llvm.fmuladd.f64(double, double, double)