Index: llvm/lib/CodeGen/CodeGenPrepare.cpp
===================================================================
--- llvm/lib/CodeGen/CodeGenPrepare.cpp
+++ llvm/lib/CodeGen/CodeGenPrepare.cpp
@@ -6122,6 +6122,7 @@
   SmallVector<Instruction *, 4> Worklist;
   Worklist.push_back(cast<Instruction>(I));
   SmallPtrSet<PHINode *, 4> PhiNodes;
+  SmallPtrSet<ConstantData *, 4> Constants;
   PhiNodes.insert(I);
   Visited.insert(I);
   SmallPtrSet<Instruction *, 4> Defs;
@@ -6164,9 +6165,10 @@
             AnyAnchored |= !isa<LoadInst>(OpBC->getOperand(0)) &&
                            !isa<ExtractElementInst>(OpBC->getOperand(0));
           }
-        } else if (!isa<UndefValue>(V)) {
+        } else if (auto *OpC = dyn_cast<ConstantData>(V))
+          Constants.insert(OpC);
+        else
           return false;
-        }
       }
     }
 
@@ -6208,7 +6210,8 @@
   // Create all the new phi nodes of the new type, and bitcast any loads to the
   // correct type.
   ValueToValueMap ValMap;
-  ValMap[UndefValue::get(PhiTy)] = UndefValue::get(ConvertTy);
+  for (ConstantData *C : Constants)
+    ValMap[C] = ConstantExpr::getCast(Instruction::BitCast, C, ConvertTy);
   for (Instruction *D : Defs) {
     if (isa<BitCastInst>(D)) {
       ValMap[D] = D->getOperand(0);
Index: llvm/test/CodeGen/AArch64/convertphitype.ll
===================================================================
--- llvm/test/CodeGen/AArch64/convertphitype.ll
+++ llvm/test/CodeGen/AArch64/convertphitype.ll
@@ -877,3 +877,111 @@
   store atomic i32 %phi, i32 *%d release, align 4
   ret void
 }
+
+define float @convphi2_zero(i32 *%s, i32 *%d, i32 %n) {
+; CHECK-LABEL: @convphi2_zero(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[CMP15:%.*]] = icmp sgt i32 [[N:%.*]], 0
+; CHECK-NEXT:    br i1 [[CMP15]], label [[THEN:%.*]], label [[END:%.*]]
+; CHECK:       then:
+; CHECK-NEXT:    [[LS:%.*]] = load i32, i32* [[S:%.*]], align 4
+; CHECK-NEXT:    [[LS_BC:%.*]] = bitcast i32 [[LS]] to float
+; CHECK-NEXT:    br label [[END]]
+; CHECK:       end:
+; CHECK-NEXT:    [[PHI_TC:%.*]] = phi float [ [[LS_BC]], [[THEN]] ], [ 0.000000e+00, [[ENTRY:%.*]] ]
+; CHECK-NEXT:    ret float [[PHI_TC]]
+;
+entry:
+  %cmp15 = icmp sgt i32 %n, 0
+  br i1 %cmp15, label %then, label %end
+
+then:
+  %ls = load i32, i32* %s, align 4
+  br label %end
+
+end:
+  %phi = phi i32 [ %ls, %then ], [ 0, %entry ]
+  %b = bitcast i32 %phi to float
+  ret float %b
+}
+
+define i32 @convphi2f_zero(float *%s, float *%d, i32 %n) {
+; CHECK-LABEL: @convphi2f_zero(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[CMP15:%.*]] = icmp sgt i32 [[N:%.*]], 0
+; CHECK-NEXT:    br i1 [[CMP15]], label [[THEN:%.*]], label [[END:%.*]]
+; CHECK:       then:
+; CHECK-NEXT:    [[LS:%.*]] = load float, float* [[S:%.*]], align 4
+; CHECK-NEXT:    [[LS_BC:%.*]] = bitcast float [[LS]] to i32
+; CHECK-NEXT:    br label [[END]]
+; CHECK:       end:
+; CHECK-NEXT:    [[PHI_TC:%.*]] = phi i32 [ [[LS_BC]], [[THEN]] ], [ 0, [[ENTRY:%.*]] ]
+; CHECK-NEXT:    ret i32 [[PHI_TC]]
+;
+entry:
+  %cmp15 = icmp sgt i32 %n, 0
+  br i1 %cmp15, label %then, label %end
+
+then:
+  %ls = load float, float* %s, align 4
+  br label %end
+
+end:
+  %phi = phi float [ %ls, %then ], [ 0.0, %entry ]
+  %b = bitcast float %phi to i32
+  ret i32 %b
+}
+
+define float @convphi2_ten(i32 *%s, i32 *%d, i32 %n) {
+; CHECK-LABEL: @convphi2_ten(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[CMP15:%.*]] = icmp sgt i32 [[N:%.*]], 0
+; CHECK-NEXT:    br i1 [[CMP15]], label [[THEN:%.*]], label [[END:%.*]]
+; CHECK:       then:
+; CHECK-NEXT:    [[LS:%.*]] = load i32, i32* [[S:%.*]], align 4
+; CHECK-NEXT:    [[LS_BC:%.*]] = bitcast i32 [[LS]] to float
+; CHECK-NEXT:    br label [[END]]
+; CHECK:       end:
+; CHECK-NEXT:    [[PHI_TC:%.*]] = phi float [ [[LS_BC]], [[THEN]] ], [ 0x36D4000000000000, [[ENTRY:%.*]] ]
+; CHECK-NEXT:    ret float [[PHI_TC]]
+;
+entry:
+  %cmp15 = icmp sgt i32 %n, 0
+  br i1 %cmp15, label %then, label %end
+
+then:
+  %ls = load i32, i32* %s, align 4
+  br label %end
+
+end:
+  %phi = phi i32 [ %ls, %then ], [ 10, %entry ]
+  %b = bitcast i32 %phi to float
+  ret float %b
+}
+
+define i32 @convphi2f_ten(float *%s, float *%d, i32 %n) {
+; CHECK-LABEL: @convphi2f_ten(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[CMP15:%.*]] = icmp sgt i32 [[N:%.*]], 0
+; CHECK-NEXT:    br i1 [[CMP15]], label [[THEN:%.*]], label [[END:%.*]]
+; CHECK:       then:
+; CHECK-NEXT:    [[LS:%.*]] = load float, float* [[S:%.*]], align 4
+; CHECK-NEXT:    [[LS_BC:%.*]] = bitcast float [[LS]] to i32
+; CHECK-NEXT:    br label [[END]]
+; CHECK:       end:
+; CHECK-NEXT:    [[PHI_TC:%.*]] = phi i32 [ [[LS_BC]], [[THEN]] ], [ 1092616192, [[ENTRY:%.*]] ]
+; CHECK-NEXT:    ret i32 [[PHI_TC]]
+;
+entry:
+  %cmp15 = icmp sgt i32 %n, 0
+  br i1 %cmp15, label %then, label %end
+
+then:
+  %ls = load float, float* %s, align 4
+  br label %end
+
+end:
+  %phi = phi float [ %ls, %then ], [ 10.0, %entry ]
+  %b = bitcast float %phi to i32
+  ret i32 %b
+}