Index: lib/Sema/SemaTemplateInstantiateDecl.cpp
===================================================================
--- lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -2175,6 +2175,11 @@
     Owner->addDecl(Method);
   }
 
+  // PR17480: Honor the used attribute to instantiate member function
+  // definitions
+  if (Method->hasAttr<UsedAttr>())
+    SemaRef.MarkFunctionReferenced(SourceLocation(), Method);
+
   return Method;
 }
 
Index: test/CodeGenCXX/attr-used-member-function-implicit-instantiation.cpp
===================================================================
--- /dev/null
+++ test/CodeGenCXX/attr-used-member-function-implicit-instantiation.cpp
@@ -0,0 +1,19 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-unknown -emit-llvm -o - %s | FileCheck %s
+
+// Check that PR17480 is fixed: __attribute__((used)) ignored in templated
+// classes
+namespace InstantiateUsedMemberDefinition {
+template <typename T>
+struct S {
+  int __attribute__((used)) f() {
+    return 0;
+  }
+};
+
+void test() {
+  // Check that InstantiateUsedMemberDefinition::S<int>::f() is defined
+  // as a result of the S class template implicit instantiation
+  // CHECK: define linkonce_odr i32 @_ZN31InstantiateUsedMemberDefinition1SIiE1fEv
+  S<int> inst;
+}
+} // namespace InstantiateUsedMemberDefinition
Index: test/SemaTemplate/attr-used-member-function-implicit-instantiation.cpp
===================================================================
--- /dev/null
+++ test/SemaTemplate/attr-used-member-function-implicit-instantiation.cpp
@@ -0,0 +1,12 @@
+// RUN: %clang_cc1 -fsyntax-only -verify %s
+
+// Check that __attribute__((used)) in member functions of templated classes
+// does not break explicit specializations of those functions
+
+// expected-no-diagnostics
+template <typename>
+struct a {
+  void verify() __attribute__((__used__));
+};
+using b = a<int>;
+template<> void b::verify() {}