Index: llvm/include/llvm/CodeGen/GlobalISel/CallLowering.h
===================================================================
--- llvm/include/llvm/CodeGen/GlobalISel/CallLowering.h
+++ llvm/include/llvm/CodeGen/GlobalISel/CallLowering.h
@@ -290,6 +290,8 @@
     return false;
   }
 
+  virtual bool fallBackToDAGISel(const Function &F) const { return false; }
+
   /// This hook must be implemented to lower the incoming (formal)
   /// arguments, described by \p VRegs, for GlobalISel. Each argument
   /// must end up in the related virtual registers described by \p VRegs.
Index: llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
===================================================================
--- llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
+++ llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
@@ -2384,6 +2384,14 @@
   // Make our arguments/constants entry block fallthrough to the IR entry block.
   EntryBB->addSuccessor(&getMBB(F.front()));
 
+  if (CLI->fallBackToDAGISel(F)) {
+    OptimizationRemarkMissed R("gisel-irtranslator", "GISelFailure",
+                               F.getSubprogram(), &F.getEntryBlock());
+    R << "unable to lower function: " << ore::NV("Prototype", F.getType());
+    reportTranslationError(*MF, *TPC, *ORE, R);
+    return false;
+  }
+
   // Lower the actual args into this basic block.
   SmallVector<ArrayRef<Register>, 8> VRegArgs;
   for (const Argument &Arg: F.args()) {
Index: llvm/lib/Target/AArch64/GISel/AArch64CallLowering.h
===================================================================
--- llvm/lib/Target/AArch64/GISel/AArch64CallLowering.h
+++ llvm/lib/Target/AArch64/GISel/AArch64CallLowering.h
@@ -37,6 +37,8 @@
                    ArrayRef<Register> VRegs,
                    Register SwiftErrorVReg) const override;
 
+  bool fallBackToDAGISel(const Function &F) const override;
+
   bool lowerFormalArguments(MachineIRBuilder &MIRBuilder, const Function &F,
                             ArrayRef<ArrayRef<Register>> VRegs) const override;
 
Index: llvm/lib/Target/AArch64/GISel/AArch64CallLowering.cpp
===================================================================
--- llvm/lib/Target/AArch64/GISel/AArch64CallLowering.cpp
+++ llvm/lib/Target/AArch64/GISel/AArch64CallLowering.cpp
@@ -427,6 +427,14 @@
   }
 }
 
+bool AArch64CallLowering::fallBackToDAGISel(const Function &F) const {
+  if (isa<ScalableVectorType>(F.getReturnType()))
+    return true;
+  return llvm::any_of(F.args(), [](const Argument &A) {
+    return isa<ScalableVectorType>(A.getType());
+  });
+}
+
 bool AArch64CallLowering::lowerFormalArguments(
     MachineIRBuilder &MIRBuilder, const Function &F,
     ArrayRef<ArrayRef<Register>> VRegs) const {
@@ -438,9 +446,6 @@
   SmallVector<ArgInfo, 8> SplitArgs;
   unsigned i = 0;
   for (auto &Arg : F.args()) {
-    if (isa<ScalableVectorType>(Arg.getType()))
-      return false;
-
     if (DL.getTypeStoreSize(Arg.getType()).isZero())
       continue;
 
Index: llvm/test/CodeGen/AArch64/GlobalISel/arm64-fallback.ll
===================================================================
--- llvm/test/CodeGen/AArch64/GlobalISel/arm64-fallback.ll
+++ llvm/test/CodeGen/AArch64/GlobalISel/arm64-fallback.ll
@@ -220,21 +220,30 @@
   ret void
 }
 
-; FALLBACK-WITH-REPORT-ERR: remark: <unknown>:0:0: unable to lower arguments{{.*}}scalable_arg
+; FALLBACK-WITH-REPORT-ERR: remark: <unknown>:0:0: unable to lower function{{.*}}scalable_arg
 ; FALLBACK-WITH-REPORT-OUT-LABEL: scalable_arg
 define <vscale x 16 x i8> @scalable_arg(<vscale x 16 x i1> %pred, i8* %addr) #1 {
   %res = call <vscale x 16 x i8> @llvm.aarch64.sve.ld1.nxv16i8(<vscale x 16 x i1> %pred, i8* %addr)
   ret <vscale x 16 x i8> %res
 }
 
-; FALLBACK-WITH-REPORT-ERR: remark: <unknown>:0:0: unable to translate instruction{{.*}}scalable_call
-; FALLBACK-WITH-REPORT-OUT-LABEL: scalable_call
-define <vscale x 16 x i8> @scalable_call(i8* %addr) #1 {
+; FALLBACK-WITH-REPORT-ERR: remark: <unknown>:0:0: unable to lower function{{.*}}scalable_ret
+; FALLBACK-WITH-REPORT-OUT-LABEL: scalable_ret
+define <vscale x 16 x i8> @scalable_ret(i8* %addr) #1 {
   %pred = call <vscale x 16 x i1> @llvm.aarch64.sve.ptrue.nxv16i1(i32 0)
   %res = call <vscale x 16 x i8> @llvm.aarch64.sve.ld1.nxv16i8(<vscale x 16 x i1> %pred, i8* %addr)
   ret <vscale x 16 x i8> %res
 }
 
+; FALLBACK-WITH-REPORT-ERR: remark: <unknown>:0:0: unable to translate instruction{{.*}}scalable_call
+; FALLBACK-WITH-REPORT-OUT-LABEL: scalable_call
+define i8 @scalable_call(i8* %addr) #1 {
+  %pred = call <vscale x 16 x i1> @llvm.aarch64.sve.ptrue.nxv16i1(i32 0)
+  %vec = call <vscale x 16 x i8> @llvm.aarch64.sve.ld1.nxv16i8(<vscale x 16 x i1> %pred, i8* %addr)
+  %res = extractelement <vscale x 16 x i8> %vec, i32 0
+  ret i8 %res
+}
+
 attributes #1 = { "target-features"="+sve" }
 
 declare <vscale x 16 x i1> @llvm.aarch64.sve.ptrue.nxv16i1(i32 %pattern)