Index: include/llvm/IR/GlobalValue.h
===================================================================
--- include/llvm/IR/GlobalValue.h
+++ include/llvm/IR/GlobalValue.h
@@ -256,7 +256,8 @@
   static bool isWeakForLinker(LinkageTypes Linkage)  {
     return Linkage == WeakAnyLinkage || Linkage == WeakODRLinkage ||
            Linkage == LinkOnceAnyLinkage || Linkage == LinkOnceODRLinkage ||
-           Linkage == CommonLinkage || Linkage == ExternalWeakLinkage;
+           Linkage == CommonLinkage || Linkage == ExternalWeakLinkage ||
+           Linkage == AvailableExternallyLinkage;
   }
 
   bool hasExternalLinkage() const { return isExternalLinkage(Linkage); }
Index: test/Transforms/GlobalOpt/available_externally_global_ctors.ll
===================================================================
--- /dev/null
+++ test/Transforms/GlobalOpt/available_externally_global_ctors.ll
@@ -0,0 +1,23 @@
+target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx10.11.0"
+
+; RUN: opt -S -globalopt < %s | FileCheck %s
+
+; Verify that the initialization of the available_externally global is not eliminated
+; CHECK: @llvm.global_ctors = appending global [1 x { i32, void ()*, i8* }] [{ i32, void ()*, i8* } { i32 65535, void ()* @foo_static_init, i8* null }]
+
+@llvm.global_ctors = appending global [1 x { i32, void ()*, i8* }] [{ i32, void ()*, i8* } { i32 65535, void ()* @foo_static_init, i8* null }]
+@foo_external = available_externally global void ()* null, align 8
+
+define internal void @foo_static_init() {
+entry:
+  store void ()* @foo_impl, void ()** @foo_external, align 8
+  ret void
+}
+
+; Function Attrs: norecurse nounwind readnone ssp uwtable
+define internal void @foo_impl() #0 {
+entry:
+  ret void
+}
+