diff --git a/llvm/lib/Target/ARM/MCTargetDesc/ARMWinCOFFObjectWriter.cpp b/llvm/lib/Target/ARM/MCTargetDesc/ARMWinCOFFObjectWriter.cpp
--- a/llvm/lib/Target/ARM/MCTargetDesc/ARMWinCOFFObjectWriter.cpp
+++ b/llvm/lib/Target/ARM/MCTargetDesc/ARMWinCOFFObjectWriter.cpp
@@ -29,7 +29,7 @@
 public:
   ARMWinCOFFObjectWriter(bool Is64Bit)
     : MCWinCOFFObjectTargetWriter(COFF::IMAGE_FILE_MACHINE_ARMNT) {
-    assert(!Is64Bit && "AArch64 support not yet implemented");
+    assert(!Is64Bit && "AArch64 is an entirely different target");
   }
 
   ~ARMWinCOFFObjectWriter() override = default;
@@ -49,7 +49,7 @@
                                               bool IsCrossSection,
                                               const MCAsmBackend &MAB) const {
   assert(getMachine() == COFF::IMAGE_FILE_MACHINE_ARMNT &&
-         "AArch64 support not yet implemented");
+         "AArch64 is an entirely different target");
 
   MCSymbolRefExpr::VariantKind Modifier =
     Target.isAbsolute() ? MCSymbolRefExpr::VK_None : Target.getSymA()->getKind();