diff --git a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
index 581f152776026..69f8c6c21a556 100644
--- a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
+++ b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
@@ -7632,7 +7632,7 @@ CCAssignFn *AArch64TargetLowering::CCAssignFnForCall(CallingConv::ID CC,
                                                      bool IsVarArg) const {
   switch (CC) {
   default:
-    report_fatal_error("Unsupported calling convention.");
+    reportFatalUsageError("unsupported calling convention");
   case CallingConv::GHC:
     return CC_AArch64_GHC;
   case CallingConv::PreserveNone:
@@ -7741,6 +7741,12 @@ SDValue AArch64TargetLowering::LowerFormalArguments(
   unsigned NumArgs = Ins.size();
   Function::const_arg_iterator CurOrigArg = F.arg_begin();
   unsigned CurArgIdx = 0;
+  bool UseVarArgCC = false;
+  if (IsWin64)
+    UseVarArgCC = isVarArg;
+
+  CCAssignFn *AssignFn = CCAssignFnForCall(CallConv, UseVarArgCC);
+
   for (unsigned i = 0; i != NumArgs; ++i) {
     MVT ValVT = Ins[i].VT;
     if (Ins[i].isOrigArg()) {
@@ -7757,10 +7763,6 @@ SDValue AArch64TargetLowering::LowerFormalArguments(
       else if (ActualMVT == MVT::i16)
         ValVT = MVT::i16;
     }
-    bool UseVarArgCC = false;
-    if (IsWin64)
-      UseVarArgCC = isVarArg;
-    CCAssignFn *AssignFn = CCAssignFnForCall(CallConv, UseVarArgCC);
     bool Res =
         AssignFn(i, ValVT, ValVT, CCValAssign::Full, Ins[i].Flags, CCInfo);
     assert(!Res && "Call operand has unhandled type");
@@ -8429,6 +8431,8 @@ static void analyzeCallOperands(const AArch64TargetLowering &TLI,
         ArgVT = MVT::i16;
     }
 
+    // FIXME: CCAssignFnForCall should be called once, for the call and not per
+    // argument. This logic should exactly mirror LowerFormalArguments.
     CCAssignFn *AssignFn = TLI.CCAssignFnForCall(CalleeCC, UseVarArgCC);
     bool Res = AssignFn(i, ArgVT, ArgVT, CCValAssign::Full, ArgFlags, CCInfo);
     assert(!Res && "Call operand has unhandled type");
diff --git a/llvm/test/CodeGen/AArch64/unsupported-cc-call.ll b/llvm/test/CodeGen/AArch64/unsupported-cc-call.ll
new file mode 100644
index 0000000000000..3e03ac81baf5a
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/unsupported-cc-call.ll
@@ -0,0 +1,8 @@
+; FIXME: This should error:
+; RUN: llc -mtriple=aarch64-- -filetype=null %s
+declare amdgpu_gfx void @amdgpu_gfx_func()
+
+define void @call_amdgpu_gfx_func() {
+  call amdgpu_gfx void @amdgpu_gfx_func()
+  ret void
+}
diff --git a/llvm/test/CodeGen/AArch64/unsupported-cc-func.ll b/llvm/test/CodeGen/AArch64/unsupported-cc-func.ll
new file mode 100644
index 0000000000000..2d0fb12af0d4a
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/unsupported-cc-func.ll
@@ -0,0 +1,6 @@
+; RUN: not llc -mtriple=aarch64-- -filetype=null %s 2>&1 | FileCheck %s
+
+; CHECK: LLVM ERROR: unsupported calling convention
+define amdgpu_gfx void @amdgpu_gfx_func_definition() {
+  ret void
+}
diff --git a/llvm/test/MC/AArch64/coff-function-type-info.ll b/llvm/test/MC/AArch64/coff-function-type-info.ll
index 21446c50ab275..63cac59adef1b 100644
--- a/llvm/test/MC/AArch64/coff-function-type-info.ll
+++ b/llvm/test/MC/AArch64/coff-function-type-info.ll
@@ -1,10 +1,10 @@
-; RUN: llc -mtriple arm64-windows -filetype asm -o - %s \
+    ; RUN: llc -mtriple arm64-windows -filetype asm -o - %s \
 ; RUN:    | FileCheck %s -check-prefix CHECK-ASM
 
 ; RUN: llc -mtriple arm64-windows -filetype obj -o - %s \
 ; RUN:    | llvm-readobj --symbols - | FileCheck %s -check-prefix CHECK-OBJECT
 
-define arm_aapcs_vfpcc void @external() {
+define aarch64_vector_pcs void @external() {
 entry:
   ret void
 }
@@ -15,7 +15,7 @@ entry:
 ; CHECK-ASM: .endef
 ; CHECK-ASM: .globl external
 
-define internal arm_aapcs_vfpcc void @internal() {
+define internal aarch64_vector_pcs void @internal() {
 entry:
   ret void
 }