Index: include/clang/Basic/Attr.td
===================================================================
--- include/clang/Basic/Attr.td
+++ include/clang/Basic/Attr.td
@@ -2472,9 +2472,9 @@
   let Documentation = [DLLImportDocs];
 }
 
-def SelectAny : InheritableAttr, TargetSpecificAttr<TargetWindows> {
+def SelectAny : InheritableAttr {
   let Spellings = [Declspec<"selectany">, GCC<"selectany">];
-  let Documentation = [Undocumented];
+  let Documentation = [SelectAnyDocs];
 }
 
 def Thread : Attr {
Index: include/clang/Basic/AttrDocs.td
===================================================================
--- include/clang/Basic/AttrDocs.td
+++ include/clang/Basic/AttrDocs.td
@@ -3149,3 +3149,9 @@
 ensure that this class cannot be subclassed.
   }];
 }
+
+
+def SelectAnyDocs : Documentation {
+   let Content = [{This attribute makes global symbol have a weak definition
+   (link-once), meaning that the linker can select any definition.}];
+}
\ No newline at end of file
Index: test/Sema/attr-selectany.c
===================================================================
--- test/Sema/attr-selectany.c
+++ test/Sema/attr-selectany.c
@@ -1,5 +1,7 @@
 // RUN: %clang_cc1 -triple x86_64-win32 -fdeclspec -verify %s
 // RUN: %clang_cc1 -triple x86_64-mingw32 -verify %s
+// RUN: %clang_cc1 -triple x86_64-unknown-linux -verify -fdeclspec %s
+// RUN: %clang_cc1 -triple x86_64-win32-macho -verify -fdeclspec %s
 
 extern __declspec(selectany) const int x1 = 1; // no warning, const means we need extern in C++
 
Index: test/SemaCXX/attr-selectany.cpp
===================================================================
--- test/SemaCXX/attr-selectany.cpp
+++ test/SemaCXX/attr-selectany.cpp
@@ -1,4 +1,7 @@
 // RUN: %clang_cc1 -triple x86_64-win32 -fms-compatibility -fms-extensions -fsyntax-only -verify -std=c++11 %s
+// RUN: %clang_cc1 -triple x86_64-unknown-linux -fms-compatibility -fms-extensions -fsyntax-only -verify -std=c++11 %s
+// RUN: %clang_cc1 -triple x86_64-win32-macho -fms-compatibility -fms-extensions -fsyntax-only -verify -std=c++11 %s
+
 // MSVC produces similar diagnostics.
 
 __declspec(selectany) void foo() { } // expected-error{{'selectany' can only be applied to data items with external linkage}}