diff --git a/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp b/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp
--- a/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp
+++ b/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp
@@ -814,7 +814,7 @@
   for (auto &P : Index) {
     for (auto &S : P.second.SummaryList) {
       auto *GVar = dyn_cast<GlobalVarSummary>(S.get());
-      if (!GVar || GVar->vTableFuncs().empty() ||
+      if (!GVar ||
           GVar->getVCallVisibility() != GlobalObject::VCallVisibilityPublic ||
           // Don't upgrade the visibility for symbols exported to the dynamic
           // linker, as we have no information on their eventual use.
@@ -1005,10 +1005,8 @@
   for (const TypeIdOffsetVtableInfo &P : TIdInfo) {
     // Find a representative copy of the vtable initializer.
     // We can have multiple available_externally, linkonce_odr and weak_odr
-    // vtable initializers, however currently clang does not attach type
-    // metadata to available_externally, and therefore the summary will not
-    // contain any vtable functions. We can also have multiple external
-    // vtable initializers in the case of comdats, which we cannot check here.
+    // vtable initializers. We can also have multiple external vtable
+    // initializers in the case of comdats, which we cannot check here.
     // The linker should give an error in this case.
     //
     // Also, handle the case of same-named local Vtables with the same path
@@ -1024,16 +1022,21 @@
         LocalFound = true;
       }
       auto *CurVS = cast<GlobalVarSummary>(S->getBaseObject());
-      if (!CurVS->vTableFuncs().empty()) {
+      if (!CurVS->vTableFuncs().empty() ||
+          // Previously clang did not attach the necessary type metadata to
+          // available_externally vtables, in which case there would not
+          // be any vtable functions listed in the summary and we need
+          // to treat this case conservatively (in case the bitcode is old).
+          // However, we will also not have any vtable functions in the
+          // case of a pure virtual base class. In that case we do want
+          // to set VS to avoid treating it conservatively.
+          !GlobalValue::isAvailableExternallyLinkage(S->linkage())) {
         VS = CurVS;
         // We cannot perform whole program devirtualization analysis on a vtable
         // with public LTO visibility.
         if (VS->getVCallVisibility() == GlobalObject::VCallVisibilityPublic)
           return false;
-      } else
-        // Currently clang will not attach the necessary type metadata to
-        // available_externally vtables.
-        assert(GlobalValue::isAvailableExternallyLinkage(S->linkage()));
+      }
     }
     // There will be no VS if all copies are available_externally having no
     // type metadata. In that case we can't safely perform WPD.
diff --git a/llvm/test/ThinLTO/X86/devirt_pure_virtual_base.ll b/llvm/test/ThinLTO/X86/devirt_pure_virtual_base.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/ThinLTO/X86/devirt_pure_virtual_base.ll
@@ -0,0 +1,112 @@
+;; Test that pure virtual base is handled correctly.
+
+;; Index based WPD
+;; Generate unsplit module with summary for ThinLTO index-based WPD.
+; RUN: opt --thinlto-bc -o %t1a.o %s
+; RUN: llvm-lto2 run %t1a.o -save-temps -pass-remarks=. \
+; RUN:   -whole-program-visibility \
+; RUN:   -o %t3a \
+; RUN:   -r=%t1a.o,_start,plx \
+; RUN:   -r=%t1a.o,_ZTV1A,p \
+; RUN:   -r=%t1a.o,_ZTV1B,p \
+; RUN:   -r=%t1a.o,_ZN1A1fEi,p \
+; RUN:   -r=%t1a.o,_ZN1A1nEi,p \
+; RUN:   -r=%t1a.o,_ZN1B1fEi,p \
+; RUN:   -r=%t1a.o,__cxa_pure_virtual, \
+; RUN:   2>&1 | FileCheck %s --check-prefix=REMARK
+; RUN: llvm-dis %t3a.1.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-IR
+
+;; Hybrid WPD
+;; Generate split module with summary for hybrid Thin/Regular LTO WPD.
+; RUN: opt --thinlto-bc --thinlto-split-lto-unit -o %t1b.o %s
+; RUN: llvm-lto2 run %t1b.o -save-temps -pass-remarks=. \
+; RUN:   -whole-program-visibility \
+; RUN:   -o %t3b \
+; RUN:   -r=%t1b.o,_start,plx \
+; RUN:   -r=%t1b.o,_ZTV1A, \
+; RUN:   -r=%t1b.o,_ZTV1B, \
+; RUN:   -r=%t1b.o,__cxa_pure_virtual, \
+; RUN:   -r=%t1b.o,_ZN1A1fEi,p \
+; RUN:   -r=%t1b.o,_ZN1A1nEi,p \
+; RUN:   -r=%t1b.o,_ZN1B1fEi,p \
+; RUN:   -r=%t1b.o,_ZTV1A,p \
+; RUN:   -r=%t1b.o,_ZTV1B,p \
+; RUN:   -r=%t1b.o,_ZN1A1nEi, \
+; RUN:   -r=%t1b.o,_ZN1B1fEi, \
+; RUN:   -r=%t1b.o,__cxa_pure_virtual, \
+; RUN:   2>&1 | FileCheck %s --check-prefix=REMARK
+; RUN: llvm-dis %t3b.1.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-IR
+
+;; Regular LTO WPD
+; RUN: opt -o %t1c.o %s
+; RUN: llvm-lto2 run %t1c.o -save-temps -pass-remarks=. \
+; RUN:   -whole-program-visibility \
+; RUN:   -o %t3c \
+; RUN:   -r=%t1c.o,_start,plx \
+; RUN:   -r=%t1c.o,_ZTV1A,p \
+; RUN:   -r=%t1c.o,_ZTV1B,p \
+; RUN:   -r=%t1c.o,_ZN1A1fEi,p \
+; RUN:   -r=%t1c.o,_ZN1A1nEi,p \
+; RUN:   -r=%t1c.o,_ZN1B1fEi,p \
+; RUN:   -r=%t1c.o,__cxa_pure_virtual, \
+; RUN:   2>&1 | FileCheck %s --check-prefix=REMARK
+; RUN: llvm-dis %t3c.0.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-IR
+
+; REMARK-DAG: single-impl: devirtualized a call to _ZN1A1nEi
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-grtev4-linux-gnu"
+
+%struct.A = type { i32 (...)** }
+%struct.B = type { %struct.A }
+
+@_ZTV1A = linkonce_odr unnamed_addr constant { [4 x i8*] } { [4 x i8*] [i8* null, i8* undef, i8* bitcast (void ()* @__cxa_pure_virtual to i8*), i8* bitcast (void ()* @__cxa_pure_virtual to i8*)] }, !type !0, !vcall_visibility !2
+@_ZTV1B = linkonce_odr unnamed_addr constant { [4 x i8*] } { [4 x i8*] [i8* null, i8* undef, i8* bitcast (i32 (%struct.B*, i32)* @_ZN1B1fEi to i8*), i8* bitcast (i32 (%struct.A*, i32)* @_ZN1A1nEi to i8*)] }, !type !0, !type !1, !vcall_visibility !2
+
+;; Prevent the vtables from being dead code eliminated.
+@llvm.used = appending global [2 x i8*] [ i8* bitcast ( { [4 x i8*] }* @_ZTV1A to i8*), i8* bitcast ( { [4 x i8*] }* @_ZTV1B to i8*)]
+
+; CHECK-IR-LABEL: define dso_local i32 @_start
+define i32 @_start(%struct.A* %obj, i32 %a) {
+entry:
+  %0 = bitcast %struct.A* %obj to i8***
+  %vtable = load i8**, i8*** %0
+  %1 = bitcast i8** %vtable to i8*
+  %p = call i1 @llvm.type.test(i8* %1, metadata !"_ZTS1A")
+  call void @llvm.assume(i1 %p)
+  %fptrptr = getelementptr i8*, i8** %vtable, i32 1
+  %2 = bitcast i8** %fptrptr to i32 (%struct.A*, i32)**
+  %fptr1 = load i32 (%struct.A*, i32)*, i32 (%struct.A*, i32)** %2, align 8
+
+  ;; Check that the call was devirtualized.
+  ; CHECK-IR: %call = tail call i32 @_ZN1A1nEi
+  ; CHECK-NODEVIRT-IR: %call = tail call i32 %fptr1
+  %call = tail call i32 %fptr1(%struct.A* nonnull %obj, i32 %a)
+
+  ret i32 %call
+}
+; CHECK-IR-LABEL: ret i32
+; CHECK-IR-NEXT: }
+
+declare i1 @llvm.type.test(i8*, metadata)
+declare void @llvm.assume(i1)
+declare void @__cxa_pure_virtual() unnamed_addr
+
+define linkonce_odr i32 @_ZN1A1fEi(%struct.A* %this, i32 %a) #0 {
+   ret i32 0
+}
+
+define linkonce_odr i32 @_ZN1A1nEi(%struct.A* %this, i32 %a) #0 {
+   ret i32 0
+}
+
+define linkonce_odr i32 @_ZN1B1fEi(%struct.B* %this, i32 %a) #0 {
+   ret i32 0
+}
+
+;; Make sure we don't inline or otherwise optimize out the direct calls.
+attributes #0 = { noinline optnone }
+
+!0 = !{i64 16, !"_ZTS1A"}
+!1 = !{i64 16, !"_ZTS1B"}
+!2 = !{i64 0}