Index: lib/Transforms/IPO/WholeProgramDevirt.cpp
===================================================================
--- lib/Transforms/IPO/WholeProgramDevirt.cpp
+++ lib/Transforms/IPO/WholeProgramDevirt.cpp
@@ -389,22 +389,33 @@
     if (!TM.Bits->GV->isConstant())
       return false;
 
-    auto Init = dyn_cast<ConstantArray>(TM.Bits->GV->getInitializer());
-    if (!Init)
-      return false;
-    ArrayType *VTableTy = Init->getType();
+    const DataLayout &DL = M.getDataLayout();
+    const Constant *I = TM.Bits->GV->getInitializer();
+    const uint64_t GlobalSlotOffset = TM.Offset + ByteOffset;
+    unsigned Op;
 
-    uint64_t ElemSize =
-        M.getDataLayout().getTypeAllocSize(VTableTy->getElementType());
-    uint64_t GlobalSlotOffset = TM.Offset + ByteOffset;
-    if (GlobalSlotOffset % ElemSize != 0)
-      return false;
+    if (auto *C = dyn_cast<ConstantStruct>(I)) {
+      const StructLayout *SL = DL.getStructLayout(C->getType());
+
+      if (GlobalSlotOffset >= SL->getSizeInBytes())
+        return false;
+
+      Op = SL->getElementContainingOffset(GlobalSlotOffset);
+    } else if (auto *C = dyn_cast<ConstantArray>(I)) {
+      ArrayType *VTableTy = C->getType();
+      const uint64_t ElemSize = DL.getTypeAllocSize(VTableTy->getElementType());
+
+      if (GlobalSlotOffset % ElemSize != 0)
+        return false;
+
+      Op = GlobalSlotOffset / ElemSize;
 
-    unsigned Op = GlobalSlotOffset / ElemSize;
-    if (Op >= Init->getNumOperands())
+      if (Op >= C->getNumOperands())
+        return false;
+    } else
       return false;
 
-    auto Fn = dyn_cast<Function>(Init->getOperand(Op)->stripPointerCasts());
+    auto Fn = dyn_cast<Function>(I->getOperand(Op)->stripPointerCasts());
     if (!Fn)
       return false;
 
Index: test/Transforms/WholeProgramDevirt/non-array-vtable.ll
===================================================================
--- test/Transforms/WholeProgramDevirt/non-array-vtable.ll
+++ test/Transforms/WholeProgramDevirt/non-array-vtable.ll
@@ -3,18 +3,21 @@
 target datalayout = "e-p:64:64"
 target triple = "x86_64-unknown-linux-gnu"
 
-@vt = constant i8* bitcast (void (i8*)* @vf to i8*), !type !0
+%vtTy = type { void (i8*)* }
+
+@vt1 = constant i8* bitcast (void (i8*)* @vf to i8*), !type !0
+@vt2 = constant %vtTy { void (i8*)* @vf }, !type !1
 
 define void @vf(i8* %this) {
   ret void
 }
 
-; CHECK: define void @call
-define void @call(i8* %obj) {
+; CHECK: define void @call1
+define void @call1(i8* %obj) {
   %vtableptr = bitcast i8* %obj to [1 x i8*]**
   %vtable = load [1 x i8*]*, [1 x i8*]** %vtableptr
   %vtablei8 = bitcast [1 x i8*]* %vtable to i8*
-  %p = call i1 @llvm.type.test(i8* %vtablei8, metadata !"typeid")
+  %p = call i1 @llvm.type.test(i8* %vtablei8, metadata !"typeid1")
   call void @llvm.assume(i1 %p)
   %fptrptr = getelementptr [1 x i8*], [1 x i8*]* %vtable, i32 0, i32 0
   %fptr = load i8*, i8** %fptrptr
@@ -24,7 +27,23 @@
   ret void
 }
 
+; CHECK: define void @call2
+define void @call2(i8* %obj) {
+  %vtableptr = bitcast i8* %obj to [1 x i8*]**
+  %vtable = load [1 x i8*]*, [1 x i8*]** %vtableptr
+  %vtablei8 = bitcast [1 x i8*]* %vtable to i8*
+  %p = call i1 @llvm.type.test(i8* %vtablei8, metadata !"typeid2")
+  call void @llvm.assume(i1 %p)
+  %fptrptr = getelementptr [1 x i8*], [1 x i8*]* %vtable, i32 0, i32 0
+  %fptr = load i8*, i8** %fptrptr
+  %fptr_casted = bitcast i8* %fptr to void (i8*)*
+  ; CHECK: call void @vf(
+  call void %fptr_casted(i8* %obj)
+  ret void
+}
+
 declare i1 @llvm.type.test(i8*, metadata)
 declare void @llvm.assume(i1)
 
-!0 = !{i32 0, !"typeid"}
+!0 = !{i32 0, !"typeid1"}
+!1 = !{i32 0, !"typeid2"}