Index: include/clang/Basic/CodeGenOptions.def
===================================================================
--- include/clang/Basic/CodeGenOptions.def
+++ include/clang/Basic/CodeGenOptions.def
@@ -356,6 +356,9 @@
 /// Whether to emit an address-significance table into the object file.
 CODEGENOPT(Addrsig, 1, 0)
 
+/// Whether to convert a switch table into a bitmap or not.
+CODEGENOPT(NoSwitchBitmap, 1, 0)
+
 ENUM_CODEGENOPT(SignReturnAddress, SignReturnAddressScope, 2, None)
 ENUM_CODEGENOPT(SignReturnAddressKey, SignReturnAddressKeyValue, 1, AKey)
 CODEGENOPT(BranchTargetEnforcement, 1, 0)
Index: include/clang/Driver/Options.td
===================================================================
--- include/clang/Driver/Options.td
+++ include/clang/Driver/Options.td
@@ -774,6 +774,10 @@
   HelpText<"Emit an address-significance table">;
 def fno_addrsig : Flag<["-"], "fno-addrsig">, Group<f_Group>, Flags<[CoreOption]>,
   HelpText<"Don't emit an address-significance table">;
+def fswitch_bitmap : Flag<["-"], "fswitch-bitmap">, Group<f_Group>, 
+    Flags<[CC1Option]>, HelpText<"Convert switch to bitmap">;
+def fno_switch_bitmap : Flag<["-"], "fno-switch-bitmap">, Group<f_Group>,
+    Flags<[CoreOption, CC1Option]>, HelpText<"Do not convert switch to bitmap">;
 def fblocks : Flag<["-"], "fblocks">, Group<f_Group>, Flags<[CoreOption, CC1Option]>,
   HelpText<"Enable the 'blocks' language feature">;
 def fbootclasspath_EQ : Joined<["-"], "fbootclasspath=">, Group<f_Group>;
Index: lib/CodeGen/BackendUtil.cpp
===================================================================
--- lib/CodeGen/BackendUtil.cpp
+++ lib/CodeGen/BackendUtil.cpp
@@ -473,6 +473,7 @@
   Options.DebuggerTuning = CodeGenOpts.getDebuggerTuning();
   Options.EmitStackSizeSection = CodeGenOpts.StackSizeSection;
   Options.EmitAddrsig = CodeGenOpts.Addrsig;
+  Options.EmitSwitchBitmap = CodeGenOpts.NoSwitchBitmap;
 
   if (CodeGenOpts.getSplitDwarfMode() != CodeGenOptions::NoFission)
     Options.MCOptions.SplitDwarfFile = CodeGenOpts.SplitDwarfFile;
@@ -558,6 +559,7 @@
   PMBuilder.PrepareForThinLTO = CodeGenOpts.PrepareForThinLTO;
   PMBuilder.PrepareForLTO = CodeGenOpts.PrepareForLTO;
   PMBuilder.RerollLoops = CodeGenOpts.RerollLoops;
+  PMBuilder.NoSwitchBitmap = CodeGenOpts.NoSwitchBitmap;
 
   MPM.add(new TargetLibraryInfoWrapperPass(*TLII));
 
Index: lib/Driver/ToolChains/Clang.cpp
===================================================================
--- lib/Driver/ToolChains/Clang.cpp
+++ lib/Driver/ToolChains/Clang.cpp
@@ -5340,6 +5340,14 @@
                        TC.useIntegratedAs()))
     CmdArgs.push_back("-faddrsig");
 
+  // If the target is Aarch64 and we are optimizing for size, we don't want to
+  // convert switch tables into bitmaps.
+  if (Args.hasFlag(options::OPT_fno_switch_bitmap, options::OPT_fswitch_bitmap,
+                   (Triple.getArch() == llvm::Triple::aarch64)) &&
+      getOptimizationLevelSize(Args)) {
+    CmdArgs.push_back("-fno-switch-bitmap");
+  }
+  
   // Finally add the compile command to the compilation.
   if (Args.hasArg(options::OPT__SLASH_fallback) &&
       Output.getType() == types::TY_Object &&
Index: lib/Frontend/CompilerInvocation.cpp
===================================================================
--- lib/Frontend/CompilerInvocation.cpp
+++ lib/Frontend/CompilerInvocation.cpp
@@ -1284,6 +1284,8 @@
 
   Opts.Addrsig = Args.hasArg(OPT_faddrsig);
 
+  Opts.NoSwitchBitmap = Args.hasArg(OPT_fno_switch_bitmap);
+
   if (Arg *A = Args.getLastArg(OPT_msign_return_address_EQ)) {
     StringRef SignScope = A->getValue();