Index: lib/Target/ARM/ARMISelLowering.cpp
===================================================================
--- lib/Target/ARM/ARMISelLowering.cpp
+++ lib/Target/ARM/ARMISelLowering.cpp
@@ -1617,6 +1617,8 @@
   case CallingConv::ARM_AAPCS:
     return (Return ? RetCC_ARM_AAPCS : CC_ARM_AAPCS);
   case CallingConv::ARM_AAPCS_VFP:
+    if (getSubtarget()->isThumb1Only() || !getSubtarget()->hasVFP2())
+      report_fatal_error("The aapcs_vfp calling convention is not supported on this target.");
     return (Return ? RetCC_ARM_AAPCS_VFP : CC_ARM_AAPCS_VFP);
   case CallingConv::Fast:
     return (Return ? RetFastCC_ARM_APCS : FastCC_ARM_APCS);
Index: test/CodeGen/ARM/aapcs-vfp-call-float-arg.ll
===================================================================
--- /dev/null
+++ test/CodeGen/ARM/aapcs-vfp-call-float-arg.ll
@@ -0,0 +1,26 @@
+; RUN: not llc %s -o - 2>&1 | FileCheck %s
+
+; ModuleID = 't-call-float-arg.c'
+source_filename = "t-call-float-arg.c"
+target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"
+target triple = "thumbv6--linux-gnueabihf"
+
+; Function Attrs: noinline nounwind optnone
+define void @g() #0 {
+; CHECK: LLVM ERROR: The aapcs_vfp calling convention is not supported on this target.
+entry:
+  call arm_aapcs_vfpcc void @f(float 1.000000e+00)
+  ret void
+}
+
+declare arm_aapcs_vfpcc void @f(float) #1
+
+attributes #0 = { noinline nounwind optnone "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="arm1136j-s" "target-features"="+dsp,+strict-align,-crypto,-d16,-fp-armv8,-fp-only-sp,-fp16,-neon,-vfp2,-vfp3,-vfp4" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="arm1136j-s" "target-features"="+dsp,+strict-align,-crypto,-d16,-fp-armv8,-fp-only-sp,-fp16,-neon,-vfp2,-vfp3,-vfp4" "unsafe-fp-math"="false" "use-soft-float"="false" }
+
+!llvm.module.flags = !{!0, !1}
+!llvm.ident = !{!2}
+
+!0 = !{i32 1, !"wchar_size", i32 4}
+!1 = !{i32 1, !"min_enum_size", i32 4}
+!2 = !{!"clang version 5.0.0 "}
Index: test/CodeGen/ARM/aapcs-vfp-call-float-result.ll
===================================================================
--- /dev/null
+++ test/CodeGen/ARM/aapcs-vfp-call-float-result.ll
@@ -0,0 +1,26 @@
+; RUN: not llc %s -o - 2>&1 | FileCheck %s
+
+; ModuleID = 't-call-float-result.c'
+source_filename = "t-call-float-result.c"
+target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"
+target triple = "thumbv6--linux-gnueabihf"
+
+; Function Attrs: noinline nounwind optnone
+define float @g() #0 {
+; CHECK: LLVM ERROR: The aapcs_vfp calling convention is not supported on this target.
+entry:
+  %call = call arm_aapcs_vfpcc float @f()
+  ret float %call
+}
+
+declare arm_aapcs_vfpcc float @f() #1
+
+attributes #0 = { noinline nounwind optnone "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="arm1136j-s" "target-features"="+dsp,+strict-align,-crypto,-d16,-fp-armv8,-fp-only-sp,-fp16,-neon,-vfp2,-vfp3,-vfp4" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="arm1136j-s" "target-features"="+dsp,+strict-align,-crypto,-d16,-fp-armv8,-fp-only-sp,-fp16,-neon,-vfp2,-vfp3,-vfp4" "unsafe-fp-math"="false" "use-soft-float"="false" }
+
+!llvm.module.flags = !{!0, !1}
+!llvm.ident = !{!2}
+
+!0 = !{i32 1, !"wchar_size", i32 4}
+!1 = !{i32 1, !"min_enum_size", i32 4}
+!2 = !{!"clang version 5.0.0 "}
Index: test/CodeGen/ARM/aapcs-vfp-def-float-arg.ll
===================================================================
--- /dev/null
+++ test/CodeGen/ARM/aapcs-vfp-def-float-arg.ll
@@ -0,0 +1,24 @@
+; RUN: not llc %s -o - 2>&1 | FileCheck %s
+
+; ModuleID = 't-def-float-arg.c'
+source_filename = "t-def-float-arg.c"
+target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"
+target triple = "thumbv6--linux-gnueabihf"
+
+; Function Attrs: noinline nounwind optnone
+define arm_aapcs_vfpcc void @f(float %x) #0 {
+; CHECK: LLVM ERROR: The aapcs_vfp calling convention is not supported on this target.
+entry:
+  %x.addr = alloca float, align 4
+  store float %x, float* %x.addr, align 4
+  ret void
+}
+
+attributes #0 = { noinline nounwind optnone "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="arm1136j-s" "target-features"="+dsp,+strict-align,-crypto,-d16,-fp-armv8,-fp-only-sp,-fp16,-neon,-vfp2,-vfp3,-vfp4" "unsafe-fp-math"="false" "use-soft-float"="false" }
+
+!llvm.module.flags = !{!0, !1}
+!llvm.ident = !{!2}
+
+!0 = !{i32 1, !"wchar_size", i32 4}
+!1 = !{i32 1, !"min_enum_size", i32 4}
+!2 = !{!"clang version 5.0.0 "}
Index: test/CodeGen/ARM/aapcs-vfp-def-float-result.ll
===================================================================
--- /dev/null
+++ test/CodeGen/ARM/aapcs-vfp-def-float-result.ll
@@ -0,0 +1,22 @@
+; RUN: not llc %s -o - 2>&1 | FileCheck %s
+
+; ModuleID = 't-def-float-result.c'
+source_filename = "t-def-float-result.c"
+target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"
+target triple = "thumbv6--linux-gnueabihf"
+
+; Function Attrs: noinline nounwind optnone
+define arm_aapcs_vfpcc float @f() #0 {
+; CHECK: LLVM ERROR: The aapcs_vfp calling convention is not supported on this target.
+entry:
+  ret float 1.000000e+00
+}
+
+attributes #0 = { noinline nounwind optnone "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="arm1136j-s" "target-features"="+dsp,+strict-align,-crypto,-d16,-fp-armv8,-fp-only-sp,-fp16,-neon,-vfp2,-vfp3,-vfp4" "unsafe-fp-math"="false" "use-soft-float"="false" }
+
+!llvm.module.flags = !{!0, !1}
+!llvm.ident = !{!2}
+
+!0 = !{i32 1, !"wchar_size", i32 4}
+!1 = !{i32 1, !"min_enum_size", i32 4}
+!2 = !{!"clang version 5.0.0 "}