diff --git a/src/xenia/cpu/backend/x64/x64_backend.cc b/src/xenia/cpu/backend/x64/x64_backend.cc
index 7f51db92b..beed2af8e 100644
--- a/src/xenia/cpu/backend/x64/x64_backend.cc
+++ b/src/xenia/cpu/backend/x64/x64_backend.cc
@@ -446,14 +446,13 @@ GuestToHostThunk X64ThunkEmitter::EmitGuestToHostThunk() {
   sub(rsp, stack_size);
 
   // Save off volatile registers.
-  // TODO(DrChat): Enable when necessary.
-  // EmitSaveVolatileRegs();
+  EmitSaveVolatileRegs();
 
   mov(rax, rcx);              // function
   mov(rcx, GetContextReg());  // context
   call(rax);
 
-  // EmitLoadVolatileRegs();
+  EmitLoadVolatileRegs();
 
   add(rsp, stack_size);
   ret();
@@ -468,21 +467,22 @@ extern "C" uint64_t ResolveFunction(void* raw_context, uint32_t target_address);
 ResolveFunctionThunk X64ThunkEmitter::EmitResolveFunctionThunk() {
   // ebx = target PPC address
   // rcx = context
-  uint32_t stack_size = 0x18;
+  const size_t stack_size = StackLayout::THUNK_STACK_SIZE;
 
   // rsp + 0 = return address
-  mov(qword[rsp + 8 * 2], rdx);
-  mov(qword[rsp + 8 * 1], rcx);
   sub(rsp, stack_size);
 
+  // Save volatile registers
+  EmitSaveVolatileRegs();
+
   mov(rcx, rsi);  // context
   mov(rdx, rbx);
   mov(rax, uint64_t(&ResolveFunction));
   call(rax);
 
+  EmitLoadVolatileRegs();
+
   add(rsp, stack_size);
-  mov(rcx, qword[rsp + 8 * 1]);
-  mov(rdx, qword[rsp + 8 * 2]);
   jmp(rax);
 
   void* fn = Emplace(stack_size);
@@ -491,34 +491,38 @@ ResolveFunctionThunk X64ThunkEmitter::EmitResolveFunctionThunk() {
 
 void X64ThunkEmitter::EmitSaveVolatileRegs() {
   // Save off volatile registers.
-  mov(qword[rsp + offsetof(StackLayout::Thunk, r[0])], rcx);
-  mov(qword[rsp + offsetof(StackLayout::Thunk, r[1])], rdx);
-  mov(qword[rsp + offsetof(StackLayout::Thunk, r[2])], r8);
-  mov(qword[rsp + offsetof(StackLayout::Thunk, r[3])], r9);
-  mov(qword[rsp + offsetof(StackLayout::Thunk, r[4])], r10);
-  mov(qword[rsp + offsetof(StackLayout::Thunk, r[5])], r11);
+  // mov(qword[rsp + offsetof(StackLayout::Thunk, r[0])], rax);
+  mov(qword[rsp + offsetof(StackLayout::Thunk, r[1])], rcx);
+  mov(qword[rsp + offsetof(StackLayout::Thunk, r[2])], rdx);
+  mov(qword[rsp + offsetof(StackLayout::Thunk, r[3])], r8);
+  mov(qword[rsp + offsetof(StackLayout::Thunk, r[4])], r9);
+  mov(qword[rsp + offsetof(StackLayout::Thunk, r[5])], r10);
+  mov(qword[rsp + offsetof(StackLayout::Thunk, r[6])], r11);
 
-  movaps(qword[rsp + offsetof(StackLayout::Thunk, xmm[0])], xmm1);
-  movaps(qword[rsp + offsetof(StackLayout::Thunk, xmm[1])], xmm2);
-  movaps(qword[rsp + offsetof(StackLayout::Thunk, xmm[2])], xmm3);
-  movaps(qword[rsp + offsetof(StackLayout::Thunk, xmm[3])], xmm4);
-  movaps(qword[rsp + offsetof(StackLayout::Thunk, xmm[4])], xmm5);
+  // movaps(qword[rsp + offsetof(StackLayout::Thunk, xmm[0])], xmm0);
+  movaps(qword[rsp + offsetof(StackLayout::Thunk, xmm[1])], xmm1);
+  movaps(qword[rsp + offsetof(StackLayout::Thunk, xmm[2])], xmm2);
+  movaps(qword[rsp + offsetof(StackLayout::Thunk, xmm[3])], xmm3);
+  movaps(qword[rsp + offsetof(StackLayout::Thunk, xmm[4])], xmm4);
+  movaps(qword[rsp + offsetof(StackLayout::Thunk, xmm[5])], xmm5);
 }
 
 void X64ThunkEmitter::EmitLoadVolatileRegs() {
   // Load volatile registers from our stack frame.
-  movaps(xmm1, qword[rsp + offsetof(StackLayout::Thunk, xmm[0])]);
-  movaps(xmm2, qword[rsp + offsetof(StackLayout::Thunk, xmm[1])]);
-  movaps(xmm3, qword[rsp + offsetof(StackLayout::Thunk, xmm[2])]);
-  movaps(xmm4, qword[rsp + offsetof(StackLayout::Thunk, xmm[3])]);
-  movaps(xmm5, qword[rsp + offsetof(StackLayout::Thunk, xmm[4])]);
+  // movaps(xmm0, qword[rsp + offsetof(StackLayout::Thunk, xmm[0])]);
+  movaps(xmm1, qword[rsp + offsetof(StackLayout::Thunk, xmm[1])]);
+  movaps(xmm2, qword[rsp + offsetof(StackLayout::Thunk, xmm[2])]);
+  movaps(xmm3, qword[rsp + offsetof(StackLayout::Thunk, xmm[3])]);
+  movaps(xmm4, qword[rsp + offsetof(StackLayout::Thunk, xmm[4])]);
+  movaps(xmm5, qword[rsp + offsetof(StackLayout::Thunk, xmm[5])]);
 
-  mov(rcx, qword[rsp + offsetof(StackLayout::Thunk, r[0])]);
-  mov(rdx, qword[rsp + offsetof(StackLayout::Thunk, r[1])]);
-  mov(r8, qword[rsp + offsetof(StackLayout::Thunk, r[2])]);
-  mov(r9, qword[rsp + offsetof(StackLayout::Thunk, r[3])]);
-  mov(r10, qword[rsp + offsetof(StackLayout::Thunk, r[4])]);
-  mov(r11, qword[rsp + offsetof(StackLayout::Thunk, r[5])]);
+  // mov(rax, qword[rsp + offsetof(StackLayout::Thunk, r[0])]);
+  mov(rcx, qword[rsp + offsetof(StackLayout::Thunk, r[1])]);
+  mov(rdx, qword[rsp + offsetof(StackLayout::Thunk, r[2])]);
+  mov(r8, qword[rsp + offsetof(StackLayout::Thunk, r[3])]);
+  mov(r9, qword[rsp + offsetof(StackLayout::Thunk, r[4])]);
+  mov(r10, qword[rsp + offsetof(StackLayout::Thunk, r[5])]);
+  mov(r11, qword[rsp + offsetof(StackLayout::Thunk, r[6])]);
 }
 
 void X64ThunkEmitter::EmitSaveNonvolatileRegs() {
diff --git a/src/xenia/cpu/backend/x64/x64_emitter.cc b/src/xenia/cpu/backend/x64/x64_emitter.cc
index 3cf7f5813..7ffd7b582 100644
--- a/src/xenia/cpu/backend/x64/x64_emitter.cc
+++ b/src/xenia/cpu/backend/x64/x64_emitter.cc
@@ -56,12 +56,13 @@ static const size_t kStashOffset = 32;
 // static const size_t kStashOffsetHigh = 32 + 32;
 
 const uint32_t X64Emitter::gpr_reg_map_[X64Emitter::GPR_COUNT] = {
-    Xbyak::Operand::RBX, Xbyak::Operand::R12, Xbyak::Operand::R13,
-    Xbyak::Operand::R14, Xbyak::Operand::R15,
+    Xbyak::Operand::RBX, Xbyak::Operand::R10, Xbyak::Operand::R11,
+    Xbyak::Operand::R12, Xbyak::Operand::R13, Xbyak::Operand::R14,
+    Xbyak::Operand::R15,
 };
 
 const uint32_t X64Emitter::xmm_reg_map_[X64Emitter::XMM_COUNT] = {
-    6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
+    4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
 };
 
 X64Emitter::X64Emitter(X64Backend* backend, XbyakAllocator* allocator)
@@ -494,30 +495,20 @@ void X64Emitter::CallExtern(const hir::Instr* instr, const Function* function) {
   }
 }
 
-void X64Emitter::CallNative(void* fn) {
-  mov(rax, reinterpret_cast<uint64_t>(fn));
-  mov(rcx, GetContextReg());
-  call(rax);
-}
+void X64Emitter::CallNative(void* fn) { CallNativeSafe(fn); }
 
 void X64Emitter::CallNative(uint64_t (*fn)(void* raw_context)) {
-  mov(rax, reinterpret_cast<uint64_t>(fn));
-  mov(rcx, GetContextReg());
-  call(rax);
+  CallNativeSafe(reinterpret_cast<void*>(fn));
 }
 
 void X64Emitter::CallNative(uint64_t (*fn)(void* raw_context, uint64_t arg0)) {
-  mov(rax, reinterpret_cast<uint64_t>(fn));
-  mov(rcx, GetContextReg());
-  call(rax);
+  CallNativeSafe(reinterpret_cast<void*>(fn));
 }
 
 void X64Emitter::CallNative(uint64_t (*fn)(void* raw_context, uint64_t arg0),
                             uint64_t arg0) {
-  mov(rax, reinterpret_cast<uint64_t>(fn));
-  mov(rcx, GetContextReg());
-  mov(rdx, arg0);
-  call(rax);
+  mov(GetNativeParam(0), arg0);
+  CallNativeSafe(reinterpret_cast<void*>(fn));
 }
 
 void X64Emitter::CallNativeSafe(void* fn) {
@@ -537,8 +528,7 @@ void X64Emitter::SetReturnAddress(uint64_t value) {
   mov(qword[rsp + StackLayout::GUEST_CALL_RET_ADDR], rax);
 }
 
-Xbyak::Reg64 X64Emitter::GetNativeParam(uint32_t param)
-{
+Xbyak::Reg64 X64Emitter::GetNativeParam(uint32_t param) {
   if (param == 0)
     return rdx;
   else if (param == 1)
diff --git a/src/xenia/cpu/backend/x64/x64_emitter.h b/src/xenia/cpu/backend/x64/x64_emitter.h
index 3fb32d58d..a35c2d2b0 100644
--- a/src/xenia/cpu/backend/x64/x64_emitter.h
+++ b/src/xenia/cpu/backend/x64/x64_emitter.h
@@ -139,13 +139,13 @@ class X64Emitter : public Xbyak::CodeGenerator {
             std::vector<SourceMapEntry>* out_source_map);
 
  public:
-  // Reserved:  rsp
+  // Reserved:  rsp, rsi, rdi
   // Scratch:   rax/rcx/rdx
   //            xmm0-2
-  // Available: rbx, r12-r15 (save to get r8-r11, rbp, rsi, rdi?)
-  //            xmm6-xmm15 (save to get xmm3-xmm5)
-  static const int GPR_COUNT = 5;
-  static const int XMM_COUNT = 10;
+  // Available: rbx, r10-r15
+  //            xmm4-xmm15 (save to get xmm3)
+  static const int GPR_COUNT = 7;
+  static const int XMM_COUNT = 12;
 
   static void SetupReg(const hir::Value* v, Xbyak::Reg8& r) {
     auto idx = gpr_reg_map_[v->reg.index];