Index: llvm/lib/IR/Globals.cpp
===================================================================
--- llvm/lib/IR/Globals.cpp
+++ llvm/lib/IR/Globals.cpp
@@ -541,5 +541,5 @@
 
 const Function *GlobalIFunc::getResolverFunction() const {
   DenseSet<const GlobalAlias *> Aliases;
-  return cast<Function>(findBaseObject(getResolver(), Aliases));
+  return dyn_cast<Function>(findBaseObject(getResolver(), Aliases));
 }
Index: llvm/lib/IR/Verifier.cpp
===================================================================
--- llvm/lib/IR/Verifier.cpp
+++ llvm/lib/IR/Verifier.cpp
@@ -415,6 +415,9 @@
     for (const GlobalAlias &GA : M.aliases())
       visitGlobalAlias(GA);
 
+    for (const GlobalIFunc &GI : M.ifuncs())
+      visitGlobalIFunc(GI);
+
     for (const NamedMDNode &NMD : M.named_metadata())
       visitNamedMDNode(NMD);
 
@@ -440,6 +443,7 @@
   void visitGlobalValue(const GlobalValue &GV);
   void visitGlobalVariable(const GlobalVariable &GV);
   void visitGlobalAlias(const GlobalAlias &GA);
+  void visitGlobalIFunc(const GlobalIFunc &GI);
   void visitAliaseeSubExpr(const GlobalAlias &A, const Constant &C);
   void visitAliaseeSubExpr(SmallPtrSetImpl<const GlobalAlias *> &Visited,
                            const GlobalAlias &A, const Constant &C);
@@ -821,6 +825,15 @@
   visitGlobalValue(GA);
 }
 
+void Verifier::visitGlobalIFunc(const GlobalIFunc &GI) {
+  const Function *Resolver = GI.getResolverFunction();
+  Assert(Resolver, "IFunc must have a Function resolver", &GI);
+  Assert(!Resolver->isDeclarationForLinker(),
+         "IFunc resolver must be a definition", &GI);
+  Assert(GI.getType() == Resolver->getFunctionType()->getReturnType(),
+         "IFunc resolver return type must match IFunc type", &GI);
+}
+
 void Verifier::visitNamedMDNode(const NamedMDNode &NMD) {
   // There used to be various other llvm.dbg.* nodes, but we don't support
   // upgrading them and we want to reserve the namespace for future uses.
Index: llvm/test/Assembler/ifunc-asm.ll
===================================================================
--- llvm/test/Assembler/ifunc-asm.ll
+++ llvm/test/Assembler/ifunc-asm.ll
@@ -2,11 +2,11 @@
 
 target triple = "x86_64-unknown-linux-gnu"
 
-@foo = ifunc i32 (i32), i64 ()* @foo_ifunc
-; CHECK: @foo = ifunc i32 (i32), i64 ()* @foo_ifunc
+@foo = ifunc i32 (i32), i32 (i32)* ()* @foo_ifunc
+; CHECK: @foo = ifunc i32 (i32), i32 (i32)* ()* @foo_ifunc
 
-define internal i64 @foo_ifunc() {
+define internal i32 (i32)* @foo_ifunc() {
 entry:
-  ret i64 0
+  ret i32 (i32)* null
 }
-; CHECK: define internal i64 @foo_ifunc()
+; CHECK: define internal i32 (i32)* @foo_ifunc()
Index: llvm/test/Assembler/ifunc-dsolocal.ll
===================================================================
--- llvm/test/Assembler/ifunc-dsolocal.ll
+++ llvm/test/Assembler/ifunc-dsolocal.ll
@@ -1,9 +1,9 @@
 ; RUN: llvm-as < %s | llvm-dis | FileCheck %s
 
-@foo = dso_local ifunc i32 (i32), i64 ()* @foo_ifunc
-; CHECK: @foo = dso_local ifunc i32 (i32), i64 ()* @foo_ifunc
+@foo = dso_local ifunc i32 (i32), i32 (i32)* ()* @foo_ifunc
+; CHECK: @foo = dso_local ifunc i32 (i32), i32 (i32)* ()* @foo_ifunc
 
-define internal i64 @foo_ifunc() {
+define internal i32 (i32)* @foo_ifunc() {
 entry:
-  ret i64 0
+  ret i32 (i32)* null
 }
Index: llvm/test/Assembler/ifunc-use-list-order.ll
===================================================================
--- llvm/test/Assembler/ifunc-use-list-order.ll
+++ llvm/test/Assembler/ifunc-use-list-order.ll
@@ -6,11 +6,11 @@
 ; Alias for ifunc.
 @alias_foo = alias void (), void ()* @foo_ifunc
 
-@foo_ifunc = ifunc void (), i8* ()* @foo_resolver
+@foo_ifunc = ifunc void (), void ()* ()* @foo_resolver
 
-define i8* @foo_resolver() {
+define void ()* @foo_resolver() {
 entry:
-  ret i8* null
+  ret void ()* null
 }
 
 ; Function referencing ifunc.
@@ -26,12 +26,11 @@
 ; Alias for function.
 @alias_bar = alias void (), void ()* @bar
 
-@bar_ifunc = ifunc void (), i8* ()* @bar2_ifunc
-@bar2_ifunc = ifunc i8* (), i8* ()* @bar_resolver
+@bar_ifunc = ifunc void (), void ()* ()* @bar_resolver
 
-define i8* @bar_resolver() {
+define void ()* @bar_resolver() {
 entry:
-  ret i8* null
+  ret void ()* null
 }
 
 ; Function referencing bar.
Index: llvm/test/Bindings/llvm-c/echo.ll
===================================================================
--- llvm/test/Bindings/llvm-c/echo.ll
+++ llvm/test/Bindings/llvm-c/echo.ll
@@ -29,11 +29,11 @@
 @aliased4 = weak alias i32, i32* @var
 @aliased5 = weak_odr alias i32, i32* @var
 
-@ifunc = ifunc i32 (i32), i64 ()* @ifunc_resolver
+@ifunc = ifunc i32 (i32), i32 (i32)* ()* @ifunc_resolver
 
-define i64 @ifunc_resolver() {
+define i32 (i32)* @ifunc_resolver() {
 entry:
-  ret i64 0
+  ret i32 (i32)* null
 }
 
 define { i64, %S* } @unpackrepack(%S %s) {
Index: llvm/test/Bitcode/compatibility-6.0.ll
===================================================================
--- llvm/test/Bitcode/compatibility-6.0.ll
+++ llvm/test/Bitcode/compatibility-6.0.ll
@@ -254,24 +254,24 @@
 ;                  <ResolverTy>* @<Resolver>
 
 ; IFunc -- Linkage
-@ifunc.external = external ifunc void (), i8* ()* @ifunc_resolver
-; CHECK: @ifunc.external = ifunc void (), i8* ()* @ifunc_resolver
-@ifunc.private = private ifunc void (), i8* ()* @ifunc_resolver
-; CHECK: @ifunc.private = private ifunc void (), i8* ()* @ifunc_resolver
-@ifunc.internal = internal ifunc void (), i8* ()* @ifunc_resolver
-; CHECK: @ifunc.internal = internal ifunc void (), i8* ()* @ifunc_resolver
+@ifunc.external = external ifunc void (), void ()* ()* @ifunc_resolver
+; CHECK: @ifunc.external = ifunc void (), void ()* ()* @ifunc_resolver
+@ifunc.private = private ifunc void (), void ()* ()* @ifunc_resolver
+; CHECK: @ifunc.private = private ifunc void (), void ()* ()* @ifunc_resolver
+@ifunc.internal = internal ifunc void (), void ()* ()* @ifunc_resolver
+; CHECK: @ifunc.internal = internal ifunc void (), void ()* ()* @ifunc_resolver
 
 ; IFunc -- Visibility
-@ifunc.default = default ifunc void (), i8* ()* @ifunc_resolver
-; CHECK: @ifunc.default = ifunc void (), i8* ()* @ifunc_resolver
-@ifunc.hidden = hidden ifunc void (), i8* ()* @ifunc_resolver
-; CHECK: @ifunc.hidden = hidden ifunc void (), i8* ()* @ifunc_resolver
-@ifunc.protected = protected ifunc void (), i8* ()* @ifunc_resolver
-; CHECK: @ifunc.protected = protected ifunc void (), i8* ()* @ifunc_resolver
-
-define i8* @ifunc_resolver() {
+@ifunc.default = default ifunc void (), void ()* ()* @ifunc_resolver
+; CHECK: @ifunc.default = ifunc void (), void ()* ()* @ifunc_resolver
+@ifunc.hidden = hidden ifunc void (), void ()* ()* @ifunc_resolver
+; CHECK: @ifunc.hidden = hidden ifunc void (), void ()* ()* @ifunc_resolver
+@ifunc.protected = protected ifunc void (), void ()* ()* @ifunc_resolver
+; CHECK: @ifunc.protected = protected ifunc void (), void ()* ()* @ifunc_resolver
+
+define void ()* @ifunc_resolver() {
 entry:
-  ret i8* null
+  ret void ()* null
 }
 
 ;; Functions
Index: llvm/test/Bitcode/compatibility.ll
===================================================================
--- llvm/test/Bitcode/compatibility.ll
+++ llvm/test/Bitcode/compatibility.ll
@@ -264,28 +264,28 @@
 ;                  <ResolverTy>* @<Resolver>
 
 ; IFunc -- Linkage
-@ifunc.external = external ifunc void (), i8* ()* @ifunc_resolver
-; CHECK: @ifunc.external = ifunc void (), i8* ()* @ifunc_resolver
-@ifunc.private = private ifunc void (), i8* ()* @ifunc_resolver
-; CHECK: @ifunc.private = private ifunc void (), i8* ()* @ifunc_resolver
-@ifunc.internal = internal ifunc void (), i8* ()* @ifunc_resolver
-; CHECK: @ifunc.internal = internal ifunc void (), i8* ()* @ifunc_resolver
+@ifunc.external = external ifunc void (), void ()* ()* @ifunc_resolver
+; CHECK: @ifunc.external = ifunc void (), void ()* ()* @ifunc_resolver
+@ifunc.private = private ifunc void (), void ()* ()* @ifunc_resolver
+; CHECK: @ifunc.private = private ifunc void (), void ()* ()* @ifunc_resolver
+@ifunc.internal = internal ifunc void (), void ()* ()* @ifunc_resolver
+; CHECK: @ifunc.internal = internal ifunc void (), void ()* ()* @ifunc_resolver
 
 ; IFunc -- Visibility
-@ifunc.default = default ifunc void (), i8* ()* @ifunc_resolver
-; CHECK: @ifunc.default = ifunc void (), i8* ()* @ifunc_resolver
-@ifunc.hidden = hidden ifunc void (), i8* ()* @ifunc_resolver
-; CHECK: @ifunc.hidden = hidden ifunc void (), i8* ()* @ifunc_resolver
-@ifunc.protected = protected ifunc void (), i8* ()* @ifunc_resolver
-; CHECK: @ifunc.protected = protected ifunc void (), i8* ()* @ifunc_resolver
+@ifunc.default = default ifunc void (), void ()* ()* @ifunc_resolver
+; CHECK: @ifunc.default = ifunc void (), void ()* ()* @ifunc_resolver
+@ifunc.hidden = hidden ifunc void (), void ()* ()* @ifunc_resolver
+; CHECK: @ifunc.hidden = hidden ifunc void (), void ()* ()* @ifunc_resolver
+@ifunc.protected = protected ifunc void (), void ()* ()* @ifunc_resolver
+; CHECK: @ifunc.protected = protected ifunc void (), void ()* ()* @ifunc_resolver
 
 ; IFunc -- partition
-; CHECK: @ifunc.partition = ifunc void (), i8* ()* @ifunc_resolver, partition "part"
-@ifunc.partition = ifunc void (), i8* ()* @ifunc_resolver, partition "part"
+; CHECK: @ifunc.partition = ifunc void (), void ()* ()* @ifunc_resolver, partition "part"
+@ifunc.partition = ifunc void (), void ()* ()* @ifunc_resolver, partition "part"
 
-define i8* @ifunc_resolver() {
+define void ()* @ifunc_resolver() {
 entry:
-  ret i8* null
+  ret void ()* null
 }
 
 ;; Functions
Index: llvm/test/Bitcode/dso_local_equivalent.ll
===================================================================
--- llvm/test/Bitcode/dso_local_equivalent.ll
+++ llvm/test/Bitcode/dso_local_equivalent.ll
@@ -65,12 +65,12 @@
   ret void
 }
 
-@ifunc_func = ifunc void (), i64 ()* @resolver
-@dso_local_ifunc_func = dso_local ifunc void (), i64 ()* @resolver
+@ifunc_func = ifunc void (), void ()* ()* @resolver
+@dso_local_ifunc_func = dso_local ifunc void (), void ()* ()* @resolver
 
-define internal i64 @resolver() {
+define internal void ()* @resolver() {
 entry:
-  ret i64 0
+  ret void ()* null
 }
 
 define void @call_ifunc_func() {
Index: llvm/test/Bitcode/dso_location.ll
===================================================================
--- llvm/test/Bitcode/dso_location.ll
+++ llvm/test/Bitcode/dso_location.ll
@@ -27,8 +27,8 @@
 @preemptable_alias = dso_preemptable alias i32, i32* @hidden_local_global
 ; CHECK-DAG: @preemptable_alias = alias i32, i32* @hidden_local_global
 
-@preemptable_ifunc = dso_preemptable ifunc void (), i8* ()* @ifunc_resolver
-; CHECK-DAG: @preemptable_ifunc = ifunc void (), i8* ()* @ifunc_resolver
+@preemptable_ifunc = dso_preemptable ifunc void (), void ()* ()* @ifunc_resolver
+; CHECK-DAG: @preemptable_ifunc = ifunc void (), void ()* ()* @ifunc_resolver
 declare dso_local default void @default_local()
 ; CHECK: declare dso_local void @default_local()
 
@@ -41,7 +41,7 @@
   ret void
 }
 
-define i8* @ifunc_resolver() {
+define void ()* @ifunc_resolver() {
 entry:
-  ret i8* null
+  ret void ()* null
 }
Index: llvm/test/CodeGen/X86/addrsig.ll
===================================================================
--- llvm/test/CodeGen/X86/addrsig.ll
+++ llvm/test/CodeGen/X86/addrsig.ll
@@ -6,9 +6,9 @@
 ; CHECK: .addrsig
 
 ; CHECK: .addrsig_sym f1
-define void @f1() {
-  %f1 = bitcast void()* @f1 to i8*
-  %f2 = bitcast void()* @f2 to i8*
+define void()* @f1() {
+  %f1 = bitcast void()* ()* @f1 to i8*
+  %f2 = bitcast void()* ()* @f2 to i8*
   %f3 = bitcast void()* @f3 to i8*
   %g1 = bitcast i32* @g1 to i8*
   %g2 = bitcast i32* @g2 to i8*
@@ -34,7 +34,7 @@
 declare void @metadata_f2()
 
 ; CHECK-NOT: .addrsig_sym f2
-define internal void @f2() local_unnamed_addr {
+define internal void()* @f2() local_unnamed_addr {
   unreachable
 }
 
@@ -63,9 +63,9 @@
 @a2 = internal local_unnamed_addr alias i32, i32* @g2
 
 ; CHECK: .addrsig_sym i1
-@i1 = ifunc void(), void()* @f1
+@i1 = ifunc void(), void()* ()* @f1
 ; CHECK-NOT: .addrsig_sym i2
-@i2 = internal local_unnamed_addr ifunc void(), void()* @f2
+@i2 = internal local_unnamed_addr ifunc void(), void()* ()* @f2
 
 declare void @llvm.dbg.value(metadata, metadata, metadata)
 
Index: llvm/test/CodeGen/X86/dso_local_equivalent.ll
===================================================================
--- llvm/test/CodeGen/X86/dso_local_equivalent.ll
+++ llvm/test/CodeGen/X86/dso_local_equivalent.ll
@@ -74,12 +74,12 @@
   ret void
 }
 
-@ifunc_func = ifunc void (), i64 ()* @resolver
-@dso_local_ifunc_func = dso_local ifunc void (), i64 ()* @resolver
+@ifunc_func = ifunc void (), void ()* ()* @resolver
+@dso_local_ifunc_func = dso_local ifunc void (), void ()* ()* @resolver
 
-define internal i64 @resolver() {
+define internal void ()* @resolver() {
 entry:
-  ret i64 0
+  ret void ()* null
 }
 
 ; If an ifunc is not dso_local already, then we should still emit a stub for it
Index: llvm/test/CodeGen/X86/ifunc-asm.ll
===================================================================
--- llvm/test/CodeGen/X86/ifunc-asm.ll
+++ llvm/test/CodeGen/X86/ifunc-asm.ll
@@ -2,13 +2,13 @@
 
 target triple = "x86_64-unknown-linux-gnu"
 
-define internal i64 @foo_ifunc() {
+define internal i32 (i32)* @foo_ifunc() {
 entry:
-  ret i64 0
+  ret i32 (i32)* null
 }
 ; CHECK: .type foo_ifunc,@function
 ; CHECK-NEXT: foo_ifunc:
 
-@foo = ifunc i32 (i32), i64 ()* @foo_ifunc
+@foo = ifunc i32 (i32), i32 (i32)* ()* @foo_ifunc
 ; CHECK:      .type foo,@gnu_indirect_function
 ; CHECK-NEXT: .set foo, foo_ifunc
Index: llvm/test/CodeGen/X86/partition.ll
===================================================================
--- llvm/test/CodeGen/X86/partition.ll
+++ llvm/test/CodeGen/X86/partition.ll
@@ -17,7 +17,7 @@
 ; CHECK-NEXT: .zero 1
 ; CHECK-NEXT: .quad i1
 
-define void @f1() partition "part1" {
+define void ()* @f1() partition "part1" {
   unreachable
 }
 
@@ -30,4 +30,4 @@
 @g1 = global i32 0, partition "part4"
 
 @a1 = alias i32, i32* @g1, partition "part5"
-@i1 = ifunc void(), void()* @f1, partition "part6"
+@i1 = ifunc void(), void()* ()* @f1, partition "part6"
Index: llvm/test/LTO/Resolution/X86/Inputs/ifunc2.ll
===================================================================
--- llvm/test/LTO/Resolution/X86/Inputs/ifunc2.ll
+++ llvm/test/LTO/Resolution/X86/Inputs/ifunc2.ll
@@ -1,6 +1,6 @@
 target datalayout = "e-p:64:64"
 target triple = "x86_64-unknown-linux-gnu"
 
-define i32 @foo_resolver() {
-  ret i32 2
+define i32 ()* @foo_resolver() {
+  ret i32 ()* inttoptr (i32 2 to i32 ()*)
 }
Index: llvm/test/LTO/Resolution/X86/ifunc.ll
===================================================================
--- llvm/test/LTO/Resolution/X86/ifunc.ll
+++ llvm/test/LTO/Resolution/X86/ifunc.ll
@@ -9,12 +9,12 @@
 target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"
 
-@foo = ifunc i32 (i32), i64 ()* @foo_resolver
+@foo = ifunc i32 (i32), i32 (i32)* ()* @foo_resolver
 @strlen = ifunc i64 (i8*), bitcast (i64 (i8*)* ()* @strlen_resolver to i64 (i8*)*)
 
-define internal i64 @foo_resolver() {
+define internal i32 (i32)* @foo_resolver() {
 entry:
-  ret i64 0
+  ret i32 (i32)* null
 }
 
 define internal i64 (i8*)* @strlen_resolver() {
Index: llvm/test/LTO/Resolution/X86/ifunc2.ll
===================================================================
--- llvm/test/LTO/Resolution/X86/ifunc2.ll
+++ llvm/test/LTO/Resolution/X86/ifunc2.ll
@@ -6,14 +6,14 @@
 target datalayout = "e-p:64:64"
 target triple = "x86_64-unknown-linux-gnu"
 
-; CHECK: @foo = ifunc i32 (), i32 ()* @foo_resolver.2
-@foo = ifunc i32 (), i32 ()* @foo_resolver
+; CHECK: @foo = ifunc i32 (), i32 ()* ()* @foo_resolver.2
+@foo = ifunc i32 (), i32 ()* ()* @foo_resolver
 
-; CHECK: define internal i32 @foo_resolver.2() {
-; CHECK-NEXT: ret i32 1
-define weak i32 @foo_resolver() {
-  ret i32 1
+; CHECK: define internal i32 ()* @foo_resolver.2() {
+; CHECK-NEXT: ret i32 ()* inttoptr (i32 1 to i32 ()*)
+define weak i32 ()* @foo_resolver() {
+  ret i32 ()* inttoptr (i32 1 to i32 ()*)
 }
 
-; CHECK: define i32 @foo_resolver() {
-; CHECK-NEXT: ret i32 2
+; CHECK: define i32 ()* @foo_resolver() {
+; CHECK-NEXT: ret i32 ()* inttoptr (i32 2 to i32 ()*)
Index: llvm/test/Object/X86/nm-ir.ll
===================================================================
--- llvm/test/Object/X86/nm-ir.ll
+++ llvm/test/Object/X86/nm-ir.ll
@@ -32,12 +32,12 @@
 @a1 = alias i32, i32* @g1
 @a2 = internal alias i32, i32* @g1
 
-define void @f1() {
+define void ()* @f1() {
   call void @f5()
-  ret void
+  ret void ()* null
 }
 
-@ifunc_f1 = ifunc void (), void ()* @f1
+@ifunc_f1 = ifunc void (), void ()* ()* @f1
 
 define internal void @f2() {
   ret void
Index: llvm/test/ThinLTO/X86/empty-module.ll
===================================================================
--- llvm/test/ThinLTO/X86/empty-module.ll
+++ llvm/test/ThinLTO/X86/empty-module.ll
@@ -10,9 +10,9 @@
 target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"
 
-@foo = ifunc i32 (i32), i64 ()* @foo_ifunc
+@foo = ifunc i32 (i32), i32 (i32)* ()* @foo_ifunc
 
-define internal i64 @foo_ifunc() {
+define internal i32 (i32)* @foo_ifunc() {
 entry:
-  ret i64 0
+  ret i32 (i32)* null
 }
Index: llvm/test/Transforms/GlobalDCE/global-ifunc.ll
===================================================================
--- llvm/test/Transforms/GlobalDCE/global-ifunc.ll
+++ llvm/test/Transforms/GlobalDCE/global-ifunc.ll
@@ -2,12 +2,12 @@
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"
 
-@if = ifunc void (), void ()* @fn
+@if = ifunc void (), void ()* ()* @fn
 
-define internal void @fn() {
+define internal void ()* @fn() {
 entry:
-  ret void
+  ret void ()* null
 }
 
-; CHECK-DAG: @if = ifunc void (), void ()* @fn
-; CHECK-DAG: define internal void @fn(
+; CHECK-DAG: @if = ifunc void (), void ()* ()* @fn
+; CHECK-DAG: define internal void ()* @fn(