diff --git a/clang/include/clang/Basic/DiagnosticDriverKinds.td b/clang/include/clang/Basic/DiagnosticDriverKinds.td
--- a/clang/include/clang/Basic/DiagnosticDriverKinds.td
+++ b/clang/include/clang/Basic/DiagnosticDriverKinds.td
@@ -29,6 +29,8 @@
   "invalid arch name '%0', %1">;
 def err_drv_invalid_riscv_ext_arch_name : Error<
   "invalid arch name '%0', %1 '%2'">;
+def err_drv_invalid_wasm_arch_name : Error<
+  "wasm64 does not exist">;
 def warn_drv_avr_mcu_not_specified : Warning<
   "no target microcontroller specified on command line, cannot "
   "link standard libraries, please pass -mmcu=<mcu name>">,
diff --git a/clang/lib/Driver/ToolChains/WebAssembly.cpp b/clang/lib/Driver/ToolChains/WebAssembly.cpp
--- a/clang/lib/Driver/ToolChains/WebAssembly.cpp
+++ b/clang/lib/Driver/ToolChains/WebAssembly.cpp
@@ -98,6 +98,9 @@
 
   assert(Triple.isArch32Bit() != Triple.isArch64Bit());
 
+  if (Triple.isArch64Bit())
+    getDriver().Diag(diag::err_drv_invalid_wasm_arch_name);
+
   getProgramPaths().push_back(getDriver().getInstalledDir());
 
   if (getTriple().getOS() == llvm::Triple::UnknownOS) {
diff --git a/clang/test/Preprocessor/wasm-target-features.c b/clang/test/Preprocessor/wasm-target-features.c
--- a/clang/test/Preprocessor/wasm-target-features.c
+++ b/clang/test/Preprocessor/wasm-target-features.c
@@ -1,108 +1,78 @@
-// RUN: %clang -E -dM %s -o - 2>&1 \
+// RUN: not %clang -E -dM %s -o - 2>&1 \
+// RUN:     -target wasm64-unknown-unknown \
+// RUN:   | FileCheck %s -check-prefix=WASM64
+//
+// WASM64: wasm64 does not exist
+
+// RUN: %clang -E -dM %s -o - 2>&1                   \
 // RUN:     -target wasm32-unknown-unknown -msimd128 \
 // RUN:   | FileCheck %s -check-prefix=SIMD128
-// RUN: %clang -E -dM %s -o - 2>&1 \
-// RUN:     -target wasm64-unknown-unknown -msimd128 \
-// RUN:   | FileCheck %s -check-prefix=SIMD128
 //
 // SIMD128:#define __wasm_simd128__ 1{{$}}
 
 // RUN: %clang -E -dM %s -o - 2>&1 \
 // RUN:     -target wasm32-unknown-unknown -munimplemented-simd128 \
 // RUN:   | FileCheck %s -check-prefix=SIMD128-UNIMPLEMENTED
-// RUN: %clang -E -dM %s -o - 2>&1 \
-// RUN:     -target wasm64-unknown-unknown -munimplemented-simd128 \
-// RUN:   | FileCheck %s -check-prefix=SIMD128-UNIMPLEMENTED
 //
 // SIMD128-UNIMPLEMENTED:#define __wasm_unimplemented_simd128__ 1{{$}}
 
 // RUN: %clang -E -dM %s -o - 2>&1 \
 // RUN:     -target wasm32-unknown-unknown -mnontrapping-fptoint \
 // RUN:   | FileCheck %s -check-prefix=NONTRAPPING-FPTOINT
-// RUN: %clang -E -dM %s -o - 2>&1 \
-// RUN:     -target wasm64-unknown-unknown -mnontrapping-fptoint \
-// RUN:   | FileCheck %s -check-prefix=NONTRAPPING-FPTOINT
 //
 // NONTRAPPING-FPTOINT:#define __wasm_nontrapping_fptoint__ 1{{$}}
 
 // RUN: %clang -E -dM %s -o - 2>&1 \
 // RUN:     -target wasm32-unknown-unknown -msign-ext \
 // RUN:   | FileCheck %s -check-prefix=SIGN-EXT
-// RUN: %clang -E -dM %s -o - 2>&1 \
-// RUN:     -target wasm64-unknown-unknown -msign-ext \
-// RUN:   | FileCheck %s -check-prefix=SIGN-EXT
 //
 // SIGN-EXT:#define __wasm_sign_ext__ 1{{$}}
 
 // RUN: %clang -E -dM %s -o - 2>&1 \
 // RUN:     -target wasm32-unknown-unknown -mexception-handling \
 // RUN:   | FileCheck %s -check-prefix=EXCEPTION-HANDLING
-// RUN: %clang -E -dM %s -o - 2>&1 \
-// RUN:     -target wasm64-unknown-unknown -mexception-handling \
-// RUN:   | FileCheck %s -check-prefix=EXCEPTION-HANDLING
 //
 // EXCEPTION-HANDLING:#define __wasm_exception_handling__ 1{{$}}
 
 // RUN: %clang -E -dM %s -o - 2>&1 \
 // RUN:     -target wasm32-unknown-unknown -mbulk-memory \
 // RUN:   | FileCheck %s -check-prefix=BULK-MEMORY
-// RUN: %clang -E -dM %s -o - 2>&1 \
-// RUN:     -target wasm64-unknown-unknown -mbulk-memory \
-// RUN:   | FileCheck %s -check-prefix=BULK-MEMORY
 //
 // BULK-MEMORY:#define __wasm_bulk_memory__ 1{{$}}
 
 // RUN: %clang -E -dM %s -o - 2>&1 \
 // RUN:     -target wasm32-unknown-unknown -matomics \
 // RUN:   | FileCheck %s -check-prefix=ATOMICS
-// RUN: %clang -E -dM %s -o - 2>&1 \
-// RUN:     -target wasm64-unknown-unknown -matomics \
-// RUN:   | FileCheck %s -check-prefix=ATOMICS
 //
 // ATOMICS:#define __wasm_atomics__ 1{{$}}
 
 // RUN: %clang -E -dM %s -o - 2>&1 \
 // RUN:     -target wasm32-unknown-unknown -pthread \
 // RUN:   | FileCheck %s -check-prefix=PTHREAD
-// RUN: %clang -E -dM %s -o - 2>&1 \
-// RUN:     -target wasm64-unknown-unknown -pthread \
-// RUN:   | FileCheck %s -check-prefix=PTHREAD
 //
 // PTHREAD:#define __wasm_atomics__ 1{{$}}
 
 // RUN: %clang -E -dM %s -o - 2>&1 \
 // RUN:     -target wasm32-unknown-unknown -mmutable-globals \
 // RUN:   | FileCheck %s -check-prefix=MUTABLE-GLOBALS
-// RUN: %clang -E -dM %s -o - 2>&1 \
-// RUN:     -target wasm64-unknown-unknown -mmutable-globals \
-// RUN:   | FileCheck %s -check-prefix=MUTABLE-GLOBALS
 //
 // MUTABLE-GLOBALS:#define __wasm_mutable_globals__ 1{{$}}
 
 // RUN: %clang -E -dM %s -o - 2>&1 \
 // RUN:     -target wasm32-unknown-unknown -mmultivalue \
 // RUN:   | FileCheck %s -check-prefix=MULTIVALUE
-// RUN: %clang -E -dM %s -o - 2>&1 \
-// RUN:     -target wasm64-unknown-unknown -mmultivalue \
-// RUN:   | FileCheck %s -check-prefix=MULTIVALUE
 //
 // MULTIVALUE:#define __wasm_multivalue__ 1{{$}}
 
 // RUN: %clang -E -dM %s -o - 2>&1 \
 // RUN:     -target wasm32-unknown-unknown -mtail-call \
 // RUN:   | FileCheck %s -check-prefix=TAIL-CALL
-// RUN: %clang -E -dM %s -o - 2>&1 \
-// RUN:     -target wasm64-unknown-unknown -mtail-call \
-// RUN:   | FileCheck %s -check-prefix=TAIL-CALL
 //
 // TAIL-CALL:#define __wasm_tail_call__ 1{{$}}
 
 // RUN: %clang -E -dM %s -o - 2>&1 \
 // RUN:     -target wasm32-unknown-unknown -mcpu=mvp \
 // RUN:   | FileCheck %s -check-prefix=MVP
-// RUN: %clang -E -dM %s -o - 2>&1 \
-// RUN:     -target wasm64-unknown-unknown -mcpu=mvp \
-// RUN:   | FileCheck %s -check-prefix=MVP
 //
 // MVP-NOT:#define __wasm_simd128__
 // MVP-NOT:#define __wasm_unimplemented_simd128__
@@ -118,9 +88,6 @@
 // RUN: %clang -E -dM %s -o - 2>&1 \
 // RUN:     -target wasm32-unknown-unknown -mcpu=bleeding-edge \
 // RUN:   | FileCheck %s -check-prefix=BLEEDING-EDGE
-// RUN: %clang -E -dM %s -o - 2>&1 \
-// RUN:     -target wasm64-unknown-unknown -mcpu=bleeding-edge \
-// RUN:   | FileCheck %s -check-prefix=BLEEDING-EDGE
 //
 // BLEEDING-EDGE-DAG:#define __wasm_nontrapping_fptoint__ 1{{$}}
 // BLEEDING-EDGE-DAG:#define __wasm_sign_ext__ 1{{$}}
@@ -134,8 +101,5 @@
 // RUN: %clang -E -dM %s -o - 2>&1 \
 // RUN:     -target wasm32-unknown-unknown -mcpu=bleeding-edge -mno-simd128 \
 // RUN:   | FileCheck %s -check-prefix=BLEEDING-EDGE-NO-SIMD128
-// RUN: %clang -E -dM %s -o - 2>&1 \
-// RUN:     -target wasm64-unknown-unknown -mcpu=bleeding-edge -mno-simd128 \
-// RUN:   | FileCheck %s -check-prefix=BLEEDING-EDGE-NO-SIMD128
 //
 // BLEEDING-EDGE-NO-SIMD128-NOT:#define __wasm_simd128__