diff --git a/llvm/include/llvm/Object/MachO.h b/llvm/include/llvm/Object/MachO.h
--- a/llvm/include/llvm/Object/MachO.h
+++ b/llvm/include/llvm/Object/MachO.h
@@ -571,6 +571,7 @@
                               const char **McpuDefault = nullptr,
                               const char **ArchFlag = nullptr);
   static bool isValidArch(StringRef ArchFlag);
+  static ArrayRef<StringRef> getValidArchs();
   static Triple getHostArch();
 
   bool isRelocatableObject() const override;
diff --git a/llvm/lib/Object/MachOObjectFile.cpp b/llvm/lib/Object/MachOObjectFile.cpp
--- a/llvm/lib/Object/MachOObjectFile.cpp
+++ b/llvm/lib/Object/MachOObjectFile.cpp
@@ -57,6 +57,11 @@
 
 } // end anonymous namespace
 
+static const std::array<StringRef, 17> validArchs = {
+    "i386",   "x86_64", "x86_64h",  "armv4t",  "arm",    "armv5e",
+    "armv6",  "armv6m", "armv7",    "armv7em", "armv7k", "armv7m",
+    "armv7s", "arm64",  "arm64_32", "ppc",     "ppc64"};
+
 static Error malformedError(const Twine &Msg) {
   return make_error<GenericBinaryError>("truncated or malformed object (" +
                                             Msg + ")",
@@ -2718,25 +2723,12 @@
 }
 
 bool MachOObjectFile::isValidArch(StringRef ArchFlag) {
-  return StringSwitch<bool>(ArchFlag)
-      .Case("i386", true)
-      .Case("x86_64", true)
-      .Case("x86_64h", true)
-      .Case("armv4t", true)
-      .Case("arm", true)
-      .Case("armv5e", true)
-      .Case("armv6", true)
-      .Case("armv6m", true)
-      .Case("armv7", true)
-      .Case("armv7em", true)
-      .Case("armv7k", true)
-      .Case("armv7m", true)
-      .Case("armv7s", true)
-      .Case("arm64", true)
-      .Case("arm64_32", true)
-      .Case("ppc", true)
-      .Case("ppc64", true)
-      .Default(false);
+  return std::find(validArchs.cbegin(), validArchs.cend(), ArchFlag) !=
+         validArchs.cend();
+}
+
+ArrayRef<StringRef> MachOObjectFile::getValidArchs() {
+  return ArrayRef<StringRef>(validArchs);
 }
 
 Triple::ArchType MachOObjectFile::getArch() const {
diff --git a/llvm/test/tools/llvm-lipo/thin-universal-binary.test b/llvm/test/tools/llvm-lipo/thin-universal-binary.test
--- a/llvm/test/tools/llvm-lipo/thin-universal-binary.test
+++ b/llvm/test/tools/llvm-lipo/thin-universal-binary.test
@@ -1,7 +1,7 @@
 # RUN: yaml2obj %s > %t
 
-# RUN: not llvm-lipo %t -thin arc -output %t.out 2>&1 | FileCheck --check-prefix=ARCH_NOT_IN_FILE %s
-# ARCH_NOT_IN_FILE: does not contain the specified architecture arc to thin it to
+# RUN: not llvm-lipo %t -thin arm64_32 -output %t.out 2>&1 | FileCheck --check-prefix=ARCH_NOT_IN_FILE %s
+# ARCH_NOT_IN_FILE: does not contain the specified architecture arm64_32 to thin it to
 
 # RUN: not llvm-lipo %t -thin aarch101 -output %t.out 2>&1 | FileCheck --check-prefix=INVALID_ARCH %s
 # INVALID_ARCH: Invalid architecture: aarch101
diff --git a/llvm/tools/llvm-lipo/llvm-lipo.cpp b/llvm/tools/llvm-lipo/llvm-lipo.cpp
--- a/llvm/tools/llvm-lipo/llvm-lipo.cpp
+++ b/llvm/tools/llvm-lipo/llvm-lipo.cpp
@@ -93,8 +93,17 @@
 } // end namespace
 
 static void validateArchitectureName(StringRef ArchitectureName) {
-  if (Triple(ArchitectureName).getArch() == Triple::ArchType::UnknownArch)
-    reportError("Invalid architecture: " + ArchitectureName);
+  if (!MachOObjectFile::isValidArch(ArchitectureName)) {
+    std::string Buf;
+    raw_string_ostream OS(Buf);
+    OS << "Invalid architecture: " << ArchitectureName
+       << "\nValid architecture flags are:";
+    ArrayRef<StringRef> valid = MachOObjectFile::getValidArchs();
+
+    for (auto arch : valid)
+      OS << " " << arch;
+    reportError(OS.str());
+  }
 }
 
 static Config parseLipoOptions(ArrayRef<const char *> ArgsArr) {