diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 1d57d8e84849..73303b985f3f 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -9693,6 +9693,10 @@ Sema::ActOnFunctionDeclarator(Scope *S, Declarator &D, DeclContext *DC,
             (D.getCXXScopeSpec().getScopeRep()->isDependent() ||
              (!Previous.empty() && CurContext->isDependentContext()))) {
           // ignore these
+        } else if (NewFD->isCPUDispatchMultiVersion() ||
+                   NewFD->isCPUSpecificMultiVersion()) {
+          // ignore this, we allow the redeclaration behavior here to create new
+          // versions of the function.
         } else {
           // The user tried to provide an out-of-line definition for a
           // function that is a member of a class or namespace, but there
diff --git a/clang/test/CodeGenCXX/attr-cpuspecific-outoflinedefs.cpp b/clang/test/CodeGenCXX/attr-cpuspecific-outoflinedefs.cpp
new file mode 100644
index 000000000000..a34a0b88e281
--- /dev/null
+++ b/clang/test/CodeGenCXX/attr-cpuspecific-outoflinedefs.cpp
@@ -0,0 +1,97 @@
+// RUN: %clang_cc1 -triple x86_64-linux-gnu -emit-llvm -o - %s | FileCheck %s --check-prefix=LINUX
+// RUN: %clang_cc1 -triple x86_64-windows-pc -fms-compatibility -emit-llvm -o - %s | FileCheck %s --check-prefix=WINDOWS
+
+struct OutOfLineDefs {
+  int foo(int);
+  int foo(int, int);
+  __attribute__((cpu_specific(atom))) int foo(int, int, int) { return 1; }
+};
+
+int __attribute__((cpu_specific(atom))) OutOfLineDefs::foo(int) {
+  return 1;
+}
+int __attribute__((cpu_specific(ivybridge))) OutOfLineDefs::foo(int) {
+  return 2;
+}
+int __attribute__((cpu_dispatch(ivybridge, atom))) OutOfLineDefs::foo(int) {
+}
+
+int __attribute__((cpu_specific(atom))) OutOfLineDefs::foo(int, int) {
+  return 1;
+}
+int __attribute__((cpu_specific(ivybridge))) OutOfLineDefs::foo(int, int) {
+  return 2;
+}
+int __attribute__((cpu_dispatch(ivybridge, atom)))
+OutOfLineDefs::foo(int, int) {
+}
+
+int __attribute__((cpu_specific(ivybridge))) OutOfLineDefs::foo(int, int, int) {
+  return 2;
+}
+int __attribute__((cpu_specific(sandybridge)))
+OutOfLineDefs::foo(int, int, int) {
+  return 3;
+}
+int __attribute__((cpu_dispatch(sandybridge, ivybridge, atom)))
+OutOfLineDefs::foo(int, int, int) {
+}
+
+// IFunc definitions, Linux only.
+// LINUX: @_ZN13OutOfLineDefs3fooEi = weak_odr alias i32 (%struct.OutOfLineDefs*, i32), i32 (%struct.OutOfLineDefs*, i32)* @_ZN13OutOfLineDefs3fooEi.ifunc
+// LINUX: @_ZN13OutOfLineDefs3fooEii = weak_odr alias i32 (%struct.OutOfLineDefs*, i32, i32), i32 (%struct.OutOfLineDefs*, i32, i32)* @_ZN13OutOfLineDefs3fooEii.ifunc
+// LINUX: @_ZN13OutOfLineDefs3fooEiii = weak_odr alias i32 (%struct.OutOfLineDefs*, i32, i32, i32), i32 (%struct.OutOfLineDefs*, i32, i32, i32)* @_ZN13OutOfLineDefs3fooEiii.ifunc
+
+// LINUX: @_ZN13OutOfLineDefs3fooEi.ifunc = weak_odr ifunc i32 (%struct.OutOfLineDefs*, i32), i32 (%struct.OutOfLineDefs*, i32)* ()* @_ZN13OutOfLineDefs3fooEi.resolver
+// LINUX: @_ZN13OutOfLineDefs3fooEii.ifunc = weak_odr ifunc i32 (%struct.OutOfLineDefs*, i32, i32), i32 (%struct.OutOfLineDefs*, i32, i32)* ()* @_ZN13OutOfLineDefs3fooEii.resolver
+// LINUX: @_ZN13OutOfLineDefs3fooEiii.ifunc = weak_odr ifunc i32 (%struct.OutOfLineDefs*, i32, i32, i32), i32 (%struct.OutOfLineDefs*, i32, i32, i32)* ()* @_ZN13OutOfLineDefs3fooEiii.resolver
+
+// Arity 1 version:
+// LINUX: define dso_local i32 @_ZN13OutOfLineDefs3fooEi.O
+// LINUX: define dso_local i32 @_ZN13OutOfLineDefs3fooEi.S
+// LINUX: define weak_odr i32 (%struct.OutOfLineDefs*, i32)* @_ZN13OutOfLineDefs3fooEi.resolver()
+// LINUX: ret i32 (%struct.OutOfLineDefs*, i32)* @_ZN13OutOfLineDefs3fooEi.S
+// LINUX: ret i32 (%struct.OutOfLineDefs*, i32)* @_ZN13OutOfLineDefs3fooEi.O
+// LINUX: call void @llvm.trap
+
+// WINDOWS: define dso_local i32 @"?foo@OutOfLineDefs@@QEAAHH@Z.O"
+// WINDOWS: define dso_local i32 @"?foo@OutOfLineDefs@@QEAAHH@Z.S"
+// WINDOWS: define weak_odr dso_local i32 @"?foo@OutOfLineDefs@@QEAAHH@Z"(%struct.OutOfLineDefs* %0, i32 %1)
+// WINDOWS: musttail call i32 @"?foo@OutOfLineDefs@@QEAAHH@Z.S"(%struct.OutOfLineDefs* %0, i32 %1)
+// WINDOWS: musttail call i32 @"?foo@OutOfLineDefs@@QEAAHH@Z.O"(%struct.OutOfLineDefs* %0, i32 %1)
+// WINDOWS: call void @llvm.trap
+
+// Arity 2 version:
+// LINUX: define dso_local i32 @_ZN13OutOfLineDefs3fooEii.O
+// LINUX: define dso_local i32 @_ZN13OutOfLineDefs3fooEii.S
+// LINUX: define weak_odr i32 (%struct.OutOfLineDefs*, i32, i32)* @_ZN13OutOfLineDefs3fooEii.resolver()
+// LINUX: ret i32 (%struct.OutOfLineDefs*, i32, i32)* @_ZN13OutOfLineDefs3fooEii.S
+// LINUX: ret i32 (%struct.OutOfLineDefs*, i32, i32)* @_ZN13OutOfLineDefs3fooEii.O
+// LINUX: call void @llvm.trap
+
+// WINDOWS: define dso_local i32 @"?foo@OutOfLineDefs@@QEAAHHH@Z.O"
+// WINDOWS: define dso_local i32 @"?foo@OutOfLineDefs@@QEAAHHH@Z.S"
+// WINDOWS: define weak_odr dso_local i32 @"?foo@OutOfLineDefs@@QEAAHHH@Z"(%struct.OutOfLineDefs* %0, i32 %1, i32 %2)
+// WINDOWS: musttail call i32 @"?foo@OutOfLineDefs@@QEAAHHH@Z.S"(%struct.OutOfLineDefs* %0, i32 %1, i32 %2)
+// WINDOWS: musttail call i32 @"?foo@OutOfLineDefs@@QEAAHHH@Z.O"(%struct.OutOfLineDefs* %0, i32 %1, i32 %2)
+// WINDOWS: call void @llvm.trap
+
+// Arity 3 version:
+// LINUX: define dso_local i32 @_ZN13OutOfLineDefs3fooEiii.S
+// LINUX: define dso_local i32 @_ZN13OutOfLineDefs3fooEiii.R
+// LINUX: define weak_odr i32 (%struct.OutOfLineDefs*, i32, i32, i32)* @_ZN13OutOfLineDefs3fooEiii.resolver()
+// LINUX: ret i32 (%struct.OutOfLineDefs*, i32, i32, i32)* @_ZN13OutOfLineDefs3fooEiii.R
+// LINUX: ret i32 (%struct.OutOfLineDefs*, i32, i32, i32)* @_ZN13OutOfLineDefs3fooEiii.S
+// LINUX: ret i32 (%struct.OutOfLineDefs*, i32, i32, i32)* @_ZN13OutOfLineDefs3fooEiii.O
+// LINUX: call void @llvm.trap
+// LINUX: define linkonce_odr i32 @_ZN13OutOfLineDefs3fooEiii.O
+
+// WINDOWS: define dso_local i32 @"?foo@OutOfLineDefs@@QEAAHHHH@Z.S"
+// WINDOWS: define dso_local i32 @"?foo@OutOfLineDefs@@QEAAHHHH@Z.R"
+// WINDOWS: define weak_odr dso_local i32 @"?foo@OutOfLineDefs@@QEAAHHHH@Z"(%struct.OutOfLineDefs* %0, i32 %1, i32 %2, i32 %3)
+// WINDOWS: musttail call i32 @"?foo@OutOfLineDefs@@QEAAHHHH@Z.R"(%struct.OutOfLineDefs* %0, i32 %1, i32 %2, i32 %3)
+// WINDOWS: musttail call i32 @"?foo@OutOfLineDefs@@QEAAHHHH@Z.S"(%struct.OutOfLineDefs* %0, i32 %1, i32 %2, i32 %3)
+// WINDOWS: musttail call i32 @"?foo@OutOfLineDefs@@QEAAHHHH@Z.O"(%struct.OutOfLineDefs* %0, i32 %1, i32 %2, i32 %3)
+// WINDOWS: call void @llvm.trap
+// WINDOWS: define linkonce_odr dso_local i32 @"?foo@OutOfLineDefs@@QEAAHHHH@Z.O"
+
diff --git a/clang/test/SemaCXX/attr-cpuspecific.cpp b/clang/test/SemaCXX/attr-cpuspecific.cpp
index 7ec8c6cd0ce2..861711b46383 100644
--- a/clang/test/SemaCXX/attr-cpuspecific.cpp
+++ b/clang/test/SemaCXX/attr-cpuspecific.cpp
@@ -98,14 +98,12 @@ struct SpecialFuncs {
   SpecialFuncs& __attribute__((cpu_specific(atom))) operator=(SpecialFuncs&&) = delete;
 };
 
-struct BadOutOfLine {
+struct OutOfLine {
   int __attribute__((cpu_specific(atom, ivybridge))) foo(int);
 };
 
-int __attribute__((cpu_specific(atom, ivybridge))) BadOutOfLine::foo(int) { return 0; }
-// expected-error@+2 {{out-of-line definition of 'foo' does not match any declaration in 'BadOutOfLine'}}
-// expected-note@-2 {{member declaration nearly matches}}
-int __attribute__((cpu_specific(sandybridge))) BadOutOfLine::foo(int) { return 1; }
+int __attribute__((cpu_specific(atom, ivybridge))) OutOfLine::foo(int) { return 0; }
+int __attribute__((cpu_specific(sandybridge))) OutOfLine::foo(int) { return 1; }
 
 // Ensure Cpp Spelling works.
 [[clang::cpu_specific(ivybridge,atom)]] int CppSpelling(){}