diff --git a/include/llvm/MC/MCELFStreamer.h b/include/llvm/MC/MCELFStreamer.h
index e26bdaed993f..6552b52712ae 100644
--- a/include/llvm/MC/MCELFStreamer.h
+++ b/include/llvm/MC/MCELFStreamer.h
@@ -49,10 +49,6 @@ class MCELFStreamer : public MCObjectStreamer {
   void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) override;
   void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
                         unsigned ByteAlignment) override;
-  void BeginCOFFSymbolDef(const MCSymbol *Symbol) override;
-  void EmitCOFFSymbolStorageClass(int StorageClass) override;
-  void EmitCOFFSymbolType(int Type) override;
-  void EndCOFFSymbolDef() override;
 
   void emitELFSize(MCSymbol *Symbol, const MCExpr *Value) override;
 
diff --git a/include/llvm/MC/MCWasmStreamer.h b/include/llvm/MC/MCWasmStreamer.h
index 24c566a959b9..64d4fbee4b0e 100644
--- a/include/llvm/MC/MCWasmStreamer.h
+++ b/include/llvm/MC/MCWasmStreamer.h
@@ -49,10 +49,6 @@ class MCWasmStreamer : public MCObjectStreamer {
   void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) override;
   void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
                         unsigned ByteAlignment) override;
-  void BeginCOFFSymbolDef(const MCSymbol *Symbol) override;
-  void EmitCOFFSymbolStorageClass(int StorageClass) override;
-  void EmitCOFFSymbolType(int Type) override;
-  void EndCOFFSymbolDef() override;
 
   void emitELFSize(MCSymbol *Symbol, const MCExpr *Value) override;
 
diff --git a/lib/MC/MCELFStreamer.cpp b/lib/MC/MCELFStreamer.cpp
index 789cf3ff3873..172440080ea3 100644
--- a/lib/MC/MCELFStreamer.cpp
+++ b/lib/MC/MCELFStreamer.cpp
@@ -625,22 +625,6 @@ void MCELFStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
   llvm_unreachable("ELF doesn't support this directive");
 }
 
-void MCELFStreamer::BeginCOFFSymbolDef(const MCSymbol *Symbol) {
-  llvm_unreachable("ELF doesn't support this directive");
-}
-
-void MCELFStreamer::EmitCOFFSymbolStorageClass(int StorageClass) {
-  llvm_unreachable("ELF doesn't support this directive");
-}
-
-void MCELFStreamer::EmitCOFFSymbolType(int Type) {
-  llvm_unreachable("ELF doesn't support this directive");
-}
-
-void MCELFStreamer::EndCOFFSymbolDef() {
-  llvm_unreachable("ELF doesn't support this directive");
-}
-
 void MCELFStreamer::EmitZerofill(MCSection *Section, MCSymbol *Symbol,
                                  uint64_t Size, unsigned ByteAlignment) {
   llvm_unreachable("ELF doesn't support this directive");
diff --git a/lib/MC/MCMachOStreamer.cpp b/lib/MC/MCMachOStreamer.cpp
index 5820d97dd792..3ed89c4cccd3 100644
--- a/lib/MC/MCMachOStreamer.cpp
+++ b/lib/MC/MCMachOStreamer.cpp
@@ -92,22 +92,6 @@ class MCMachOStreamer : public MCObjectStreamer {
   void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
                         unsigned ByteAlignment) override;
 
-  void BeginCOFFSymbolDef(const MCSymbol *Symbol) override {
-    llvm_unreachable("macho doesn't support this directive");
-  }
-
-  void EmitCOFFSymbolStorageClass(int StorageClass) override {
-    llvm_unreachable("macho doesn't support this directive");
-  }
-
-  void EmitCOFFSymbolType(int Type) override {
-    llvm_unreachable("macho doesn't support this directive");
-  }
-
-  void EndCOFFSymbolDef() override {
-    llvm_unreachable("macho doesn't support this directive");
-  }
-
   void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
                              unsigned ByteAlignment) override;
   void EmitZerofill(MCSection *Section, MCSymbol *Symbol = nullptr,
diff --git a/lib/MC/MCStreamer.cpp b/lib/MC/MCStreamer.cpp
index cdecd48693a5..860c1bd6d877 100644
--- a/lib/MC/MCStreamer.cpp
+++ b/lib/MC/MCStreamer.cpp
@@ -807,11 +807,19 @@ void MCStreamer::emitAbsoluteSymbolDiff(const MCSymbol *Hi, const MCSymbol *Lo,
 void MCStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {}
 void MCStreamer::EmitThumbFunc(MCSymbol *Func) {}
 void MCStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {}
-void MCStreamer::BeginCOFFSymbolDef(const MCSymbol *Symbol) {}
-void MCStreamer::EndCOFFSymbolDef() {}
+void MCStreamer::BeginCOFFSymbolDef(const MCSymbol *Symbol) {
+  llvm_unreachable("this directive only supported on COFF targets");
+}
+void MCStreamer::EndCOFFSymbolDef() {
+  llvm_unreachable("this directive only supported on COFF targets");
+}
 void MCStreamer::EmitFileDirective(StringRef Filename) {}
-void MCStreamer::EmitCOFFSymbolStorageClass(int StorageClass) {}
-void MCStreamer::EmitCOFFSymbolType(int Type) {}
+void MCStreamer::EmitCOFFSymbolStorageClass(int StorageClass) {
+  llvm_unreachable("this directive only supported on COFF targets");
+}
+void MCStreamer::EmitCOFFSymbolType(int Type) {
+  llvm_unreachable("this directive only supported on COFF targets");
+}
 void MCStreamer::emitELFSize(MCSymbol *Symbol, const MCExpr *Value) {}
 void MCStreamer::EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
                                        unsigned ByteAlignment) {}
diff --git a/lib/MC/MCWasmStreamer.cpp b/lib/MC/MCWasmStreamer.cpp
index 11a00adca65f..708050b399b2 100644
--- a/lib/MC/MCWasmStreamer.cpp
+++ b/lib/MC/MCWasmStreamer.cpp
@@ -212,22 +212,6 @@ void MCWasmStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
   llvm_unreachable("Wasm doesn't support this directive");
 }
 
-void MCWasmStreamer::BeginCOFFSymbolDef(const MCSymbol *Symbol) {
-  llvm_unreachable("Wasm doesn't support this directive");
-}
-
-void MCWasmStreamer::EmitCOFFSymbolStorageClass(int StorageClass) {
-  llvm_unreachable("Wasm doesn't support this directive");
-}
-
-void MCWasmStreamer::EmitCOFFSymbolType(int Type) {
-  llvm_unreachable("Wasm doesn't support this directive");
-}
-
-void MCWasmStreamer::EndCOFFSymbolDef() {
-  llvm_unreachable("Wasm doesn't support this directive");
-}
-
 void MCWasmStreamer::EmitZerofill(MCSection *Section, MCSymbol *Symbol,
                                   uint64_t Size, unsigned ByteAlignment) {
   llvm_unreachable("Wasm doesn't support this directive");