Index: llvm/lib/LTO/LTOCodeGenerator.cpp
===================================================================
--- llvm/lib/LTO/LTOCodeGenerator.cpp
+++ llvm/lib/LTO/LTOCodeGenerator.cpp
@@ -339,15 +339,21 @@
   FeatureStr = Features.getString();
   // Set a default CPU for Darwin triples.
   if (Config.CPU.empty() && Triple.isOSDarwin()) {
-    if (Triple.getArch() == llvm::Triple::x86_64)
+    switch (Triple.getArch()) {
+    case llvm::Triple::x86_64:
       Config.CPU = "core2";
-    else if (Triple.getArch() == llvm::Triple::x86)
+      break;
+    case llvm::Triple::x86:
       Config.CPU = "yonah";
-    else if (Triple.isArm64e())
-      Config.CPU = "apple-a12";
-    else if (Triple.getArch() == llvm::Triple::aarch64 ||
-             Triple.getArch() == llvm::Triple::aarch64_32)
+      break;
+    case llvm::Triple::aarch64:
+      if (Triple.isArm64e())
+        Config.CPU = "apple-a12";
+      LLVM_FALLTHROUGH;
+    case llvm::Triple::aarch64_32:
       Config.CPU = "cyclone";
+      break;
+    }
   }
 
   TargetMach = createTargetMachine();
Index: llvm/lib/LTO/ThinLTOCodeGenerator.cpp
===================================================================
--- llvm/lib/LTO/ThinLTOCodeGenerator.cpp
+++ llvm/lib/LTO/ThinLTOCodeGenerator.cpp
@@ -588,15 +588,22 @@
 static void initTMBuilder(TargetMachineBuilder &TMBuilder,
                           const Triple &TheTriple) {
   // Set a default CPU for Darwin triples (copied from LTOCodeGenerator).
-  // FIXME this looks pretty terrible...
   if (TMBuilder.MCpu.empty() && TheTriple.isOSDarwin()) {
-    if (TheTriple.getArch() == llvm::Triple::x86_64)
+    switch (TheTriple.getArch()) {
+    case llvm::Triple::x86_64:
       TMBuilder.MCpu = "core2";
-    else if (TheTriple.getArch() == llvm::Triple::x86)
+      break;
+    case llvm::Triple::x86:
       TMBuilder.MCpu = "yonah";
-    else if (TheTriple.getArch() == llvm::Triple::aarch64 ||
-             TheTriple.getArch() == llvm::Triple::aarch64_32)
+      break;
+    case llvm::Triple::aarch64:
+      if (TheTriple.isArm64e())
+        TMBuilder.MCpu = "apple-a12";
+      LLVM_FALLTHROUGH;
+    case llvm::Triple::aarch64_32:
       TMBuilder.MCpu = "cyclone";
+      break;
+    }
   }
   TMBuilder.TheTriple = std::move(TheTriple);
 }