diff --git a/clang/lib/CodeGen/CodeGenModule.h b/clang/lib/CodeGen/CodeGenModule.h
--- a/clang/lib/CodeGen/CodeGenModule.h
+++ b/clang/lib/CodeGen/CodeGenModule.h
@@ -42,6 +42,7 @@
 class Constant;
 class ConstantInt;
 class Function;
+class GlobalIFunc;
 class GlobalValue;
 class DataLayout;
 class FunctionType;
@@ -352,6 +353,10 @@
   /// we properly emit the iFunc.
   std::vector<GlobalDecl> MultiVersionFuncs;
 
+  /// List of multiversion IFuncs we have emitted. Used to downgrade into
+  /// function declarations when we do not emit a definition for the resolver.
+  std::vector<llvm::GlobalIFunc *> MultiVersionIFuncs;
+
   typedef llvm::StringMap<llvm::TrackingVH<llvm::Constant> > ReplacementsTy;
   ReplacementsTy Replacements;
 
@@ -1555,6 +1560,10 @@
 
   void emitMultiVersionFunctions();
 
+  /// Replace multiversion IFuncs whose resolver is undefined with function
+  /// declarations.
+  void replaceUndefinedMultiVersionIFuncs();
+
   /// Emit any vtables which we deferred and still have a use for.
   void EmitDeferredVTables();
 
diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -508,6 +508,7 @@
   applyReplacements();
   checkAliases();
   emitMultiVersionFunctions();
+  replaceUndefinedMultiVersionIFuncs();
   EmitCXXGlobalInitFunc();
   EmitCXXGlobalCleanUpFunc();
   registerGlobalDtorsWithAtExit();
@@ -3289,6 +3290,22 @@
     EmitGlobalFunctionDefinition(GD, GV);
 }
 
+void CodeGenModule::replaceUndefinedMultiVersionIFuncs() {
+  for (llvm::GlobalIFunc *GIF : MultiVersionIFuncs) {
+    llvm::Function *Resolver = GIF->getResolverFunction();
+    if (!Resolver->isDeclaration())
+      continue;
+
+    auto *DeclTy = cast<llvm::FunctionType>(GIF->getValueType());
+    auto *Decl =
+        llvm::Function::Create(DeclTy, llvm::Function::ExternalLinkage,
+                               GIF->getAddressSpace(), "", &getModule());
+    Decl->takeName(GIF);
+    GIF->replaceAllUsesWith(Decl);
+    GIF->eraseFromParent();
+  }
+}
+
 void CodeGenModule::EmitGlobalDefinition(GlobalDecl GD, llvm::GlobalValue *GV) {
   const auto *D = cast<ValueDecl>(GD.getDecl());
 
@@ -3663,6 +3680,7 @@
                                   "", Resolver, &getModule());
     GIF->setName(ResolverName);
     SetCommonAttributes(FD, GIF);
+    MultiVersionIFuncs.push_back(GIF);
 
     return GIF;
   }
diff --git a/clang/test/CodeGen/attr-cpuspecific.c b/clang/test/CodeGen/attr-cpuspecific.c
--- a/clang/test/CodeGen/attr-cpuspecific.c
+++ b/clang/test/CodeGen/attr-cpuspecific.c
@@ -8,6 +8,7 @@
 #endif // _MSC_VER
 
 // Each version should have an IFunc and an alias.
+// LINUX: @SingleVersion = weak_odr alias void (), void ()* @SingleVersion.ifunc
 // LINUX: @TwoVersions = weak_odr alias void (), void ()* @TwoVersions.ifunc
 // LINUX: @TwoVersionsSameAttr = weak_odr alias void (), void ()* @TwoVersionsSameAttr.ifunc
 // LINUX: @ThreeVersionsSameAttr = weak_odr alias void (), void ()* @ThreeVersionsSameAttr.ifunc
@@ -18,8 +19,8 @@
 // LINUX: @GenericAndPentium = weak_odr alias i32 (i32, double), i32 (i32, double)* @GenericAndPentium.ifunc
 // LINUX: @DispatchFirst = weak_odr alias i32 (), i32 ()* @DispatchFirst.ifunc
 
-// LINUX: @TwoVersions.ifunc = weak_odr ifunc void (), void ()* ()* @TwoVersions.resolver
 // LINUX: @SingleVersion.ifunc = weak_odr ifunc void (), void ()* ()* @SingleVersion.resolver
+// LINUX: @TwoVersions.ifunc = weak_odr ifunc void (), void ()* ()* @TwoVersions.resolver
 // LINUX: @TwoVersionsSameAttr.ifunc = weak_odr ifunc void (), void ()* ()* @TwoVersionsSameAttr.resolver
 // LINUX: @ThreeVersionsSameAttr.ifunc = weak_odr ifunc void (), void ()* ()* @ThreeVersionsSameAttr.resolver
 // LINUX: @NoSpecifics.ifunc = weak_odr ifunc void (), void ()* ()* @NoSpecifics.resolver
@@ -34,6 +35,21 @@
 // LINUX: define{{.*}} void @SingleVersion.S() #[[S:[0-9]+]]
 // WINDOWS: define dso_local void @SingleVersion.S() #[[S:[0-9]+]]
 
+ATTR(cpu_dispatch(ivybridge))
+void SingleVersion(void);
+// LINUX: define weak_odr void ()* @SingleVersion.resolver()
+// LINUX: call void @__cpu_indicator_init
+// LINUX: ret void ()* @SingleVersion.S
+// LINUX: call void @llvm.trap
+// LINUX: unreachable
+
+// WINDOWS: define weak_odr dso_local void @SingleVersion() comdat
+// WINDOWS: call void @__cpu_indicator_init()
+// WINDOWS: call void @SingleVersion.S()
+// WINDOWS-NEXT: ret void
+// WINDOWS: call void @llvm.trap
+// WINDOWS: unreachable
+
 ATTR(cpu_specific(ivybridge))
 void NotCalled(void){}
 // LINUX: define{{.*}} void @NotCalled.S() #[[S]]
@@ -80,6 +96,10 @@
 // CHECK: define {{.*}}void @ThreeVersionsSameAttr.S() #[[S]]
 // CHECK: define {{.*}}void @ThreeVersionsSameAttr.Z() #[[K]]
 
+ATTR(cpu_specific(knl))
+int CpuSpecificNoDispatch(void) { return 1; }
+// CHECK: define {{.*}}i32 @CpuSpecificNoDispatch.Z() #[[K:[0-9]+]]
+
 void usages(void) {
   SingleVersion();
   // LINUX: @SingleVersion.ifunc()
@@ -93,6 +113,9 @@
   ThreeVersionsSameAttr();
   // LINUX: @ThreeVersionsSameAttr.ifunc()
   // WINDOWS: @ThreeVersionsSameAttr()
+  CpuSpecificNoDispatch();
+  // LINUX: @CpuSpecificNoDispatch.ifunc()
+  // WINDOWS: @CpuSpecificNoDispatch()
 }
 
 // has an extra config to emit!