diff --git a/Source/Core/Common/BitSet.h b/Source/Core/Common/BitSet.h
index 87e00385547..dfe362cbbc3 100644
--- a/Source/Core/Common/BitSet.h
+++ b/Source/Core/Common/BitSet.h
@@ -57,6 +57,10 @@ public:
   class Iterator
   {
   public:
+    using value_type = int;
+    using difference_type = std::ptrdiff_t;
+
+    constexpr Iterator() = default;
     constexpr Iterator(const Iterator& other) : m_val(other.m_val), m_bit(other.m_bit) {}
     constexpr Iterator(IntTy val, int bit) : m_val(val), m_bit(bit) {}
     Iterator& operator=(Iterator other)
@@ -89,8 +93,8 @@ public:
     constexpr bool operator!=(Iterator other) const { return m_bit != other.m_bit; }
 
   private:
-    IntTy m_val;
-    int m_bit;
+    IntTy m_val = 0;
+    int m_bit = -1;
   };
 
   constexpr BitSet() = default;
diff --git a/Source/Core/Common/x64ABI.cpp b/Source/Core/Common/x64ABI.cpp
index 9f45c132a6c..5144cb02882 100644
--- a/Source/Core/Common/x64ABI.cpp
+++ b/Source/Core/Common/x64ABI.cpp
@@ -3,6 +3,11 @@
 
 #include "Common/x64ABI.h"
 
+#include <algorithm>
+#include <array>
+#include <optional>
+
+#include "Common/Assert.h"
 #include "Common/CommonTypes.h"
 #include "Common/x64Emitter.h"
 
@@ -40,6 +45,81 @@ void XEmitter::ABI_CalculateFrameSize(BitSet32 mask, size_t rsp_alignment, size_
   *xmm_offsetp = subtraction - xmm_base_subtraction;
 }
 
+// This is using a hand-rolled algorithm. The goal is zero memory allocations, not necessarily
+// the best JIT-time time complexity. (The number of moves is usually very small.)
+void XEmitter::ParallelMoves(RegisterMove* begin, RegisterMove* end,
+                             std::array<u8, 16>* source_reg_uses,
+                             std::array<u8, 16>* destination_reg_uses)
+{
+  while (begin != end)
+  {
+    bool removed_moves_during_this_loop_iteration = false;
+
+    RegisterMove* move = end;
+    while (move != begin)
+    {
+      RegisterMove* prev_move = move;
+      --move;
+
+      const auto destination_reg_uses_minus_this_source = [&] {
+        return (*source_reg_uses)[move->destination] -
+               (move->source.GetBaseReg() == move->destination) -
+               (move->source.GetIndexReg() == move->destination);
+      };
+
+      if (destination_reg_uses_minus_this_source() == 0)
+      {
+        // TODO: Use sign extension instead of zero extension if the relevant type is signed.
+        if (move->bits < 32)
+          MOVZX(32, move->bits, move->destination, move->source);
+        else
+          MOV(move->bits, R(move->destination), move->source);
+
+        (*destination_reg_uses)[move->destination]++;
+        if (const std::optional<X64Reg> base_reg = move->source.GetBaseReg())
+          (*source_reg_uses)[*base_reg]--;
+        if (const std::optional<X64Reg> index_reg = move->source.GetIndexReg())
+          (*source_reg_uses)[*index_reg]--;
+
+        std::move(prev_move, end, move);
+        --end;
+        removed_moves_during_this_loop_iteration = true;
+      }
+    }
+
+    if (!removed_moves_during_this_loop_iteration)
+    {
+      // We need to break a cycle using a temporary register.
+
+      const BitSet32 temp_reg_candidates = ABI_ALL_CALLER_SAVED & ABI_ALL_GPRS;
+      const auto temp_reg =
+          std::find_if(temp_reg_candidates.begin(), temp_reg_candidates.end(), [&](int reg) {
+            return (*source_reg_uses)[reg] == 0 && (*destination_reg_uses)[reg] == 0;
+          });
+      ASSERT_MSG(COMMON, temp_reg != temp_reg_candidates.end(), "Out of registers");
+
+      const X64Reg source = begin->destination;
+      const X64Reg destination = static_cast<X64Reg>(*temp_reg);
+
+      const bool need_64_bit_move = std::any_of(begin, end, [source](const RegisterMove& m) {
+        return (m.source.GetBaseReg() == source || m.source.GetIndexReg() == source) &&
+               (m.source.scale != SCALE_NONE || m.bits == 64);
+      });
+
+      MOV(need_64_bit_move ? 64 : 32, R(destination), R(source));
+      (*source_reg_uses)[destination] = (*source_reg_uses)[source];
+      (*source_reg_uses)[source] = 0;
+
+      std::for_each(begin, end, [source, destination](RegisterMove& m) {
+        if (m.source.GetBaseReg() == source)
+          m.source.offsetOrBaseReg = destination;
+        if (m.source.GetIndexReg() == source)
+          m.source.indexReg = destination;
+      });
+    }
+  }
+}
+
 size_t XEmitter::ABI_PushRegistersAndAdjustStack(BitSet32 mask, size_t rsp_alignment,
                                                  size_t needed_frame_size)
 {
diff --git a/Source/Core/Common/x64ABI.h b/Source/Core/Common/x64ABI.h
index 76e82e47800..8e0637b6aa7 100644
--- a/Source/Core/Common/x64ABI.h
+++ b/Source/Core/Common/x64ABI.h
@@ -3,6 +3,8 @@
 
 #pragma once
 
+#include <array>
+
 #include "Common/BitSet.h"
 #include "Common/x64Reg.h"
 
@@ -24,34 +26,46 @@
 // Callee-save:  RBX RBP R12 R13 R14 R15
 // Parameters:   RDI RSI RDX RCX R8 R9
 
-#define ABI_ALL_FPRS BitSet32(0xffff0000)
-#define ABI_ALL_GPRS BitSet32(0x0000ffff)
+namespace Gen
+{
+
+constexpr BitSet32 ABI_ALL_FPRS(0xffff0000);
+constexpr BitSet32 ABI_ALL_GPRS(0x0000ffff);
 
 #ifdef _WIN32  // 64-bit Windows - the really exotic calling convention
 
-#define ABI_PARAM1 RCX
-#define ABI_PARAM2 RDX
-#define ABI_PARAM3 R8
-#define ABI_PARAM4 R9
+constexpr X64Reg ABI_PARAM1 = RCX;
+constexpr X64Reg ABI_PARAM2 = RDX;
+constexpr X64Reg ABI_PARAM3 = R8;
+constexpr X64Reg ABI_PARAM4 = R9;
+
+constexpr std::array<X64Reg, 4> ABI_PARAMS = {ABI_PARAM1, ABI_PARAM2, ABI_PARAM3, ABI_PARAM4};
 
 // xmm0-xmm15 use the upper 16 bits in the functions that push/pop registers.
-#define ABI_ALL_CALLER_SAVED                                                                       \
-  (BitSet32{RAX, RCX, RDX, R8, R9, R10, R11, XMM0 + 16, XMM1 + 16, XMM2 + 16, XMM3 + 16,           \
-            XMM4 + 16, XMM5 + 16})
-#else  // 64-bit Unix / OS X
+constexpr BitSet32 ABI_ALL_CALLER_SAVED{RAX,       RCX,       RDX,       R8,        R9,
+                                        R10,       R11,       XMM0 + 16, XMM1 + 16, XMM2 + 16,
+                                        XMM3 + 16, XMM4 + 16, XMM5 + 16};
 
-#define ABI_PARAM1 RDI
-#define ABI_PARAM2 RSI
-#define ABI_PARAM3 RDX
-#define ABI_PARAM4 RCX
-#define ABI_PARAM5 R8
-#define ABI_PARAM6 R9
+#else   // 64-bit Unix / OS X
+
+constexpr X64Reg ABI_PARAM1 = RDI;
+constexpr X64Reg ABI_PARAM2 = RSI;
+constexpr X64Reg ABI_PARAM3 = RDX;
+constexpr X64Reg ABI_PARAM4 = RCX;
+constexpr X64Reg ABI_PARAM5 = R8;
+constexpr X64Reg ABI_PARAM6 = R9;
+
+constexpr std::array<X64Reg, 6> ABI_PARAMS = {ABI_PARAM1, ABI_PARAM2, ABI_PARAM3,
+                                              ABI_PARAM4, ABI_PARAM5, ABI_PARAM6};
 
 // FIXME: avoid pushing all 16 XMM registers when possible? most functions we call probably
 // don't actually clobber them.
-#define ABI_ALL_CALLER_SAVED (BitSet32{RAX, RCX, RDX, RDI, RSI, R8, R9, R10, R11} | ABI_ALL_FPRS)
+constexpr BitSet32 ABI_ALL_CALLER_SAVED(BitSet32{RAX, RCX, RDX, RDI, RSI, R8, R9, R10, R11} |
+                                        ABI_ALL_FPRS);
 #endif  // _WIN32
 
-#define ABI_ALL_CALLEE_SAVED (~ABI_ALL_CALLER_SAVED)
+constexpr BitSet32 ABI_ALL_CALLEE_SAVED(~ABI_ALL_CALLER_SAVED);
 
-#define ABI_RETURN RAX
+constexpr X64Reg ABI_RETURN = RAX;
+
+};  // namespace Gen
diff --git a/Source/Core/Common/x64Emitter.h b/Source/Core/Common/x64Emitter.h
index 71dcea30f9f..71c6f6bd984 100644
--- a/Source/Core/Common/x64Emitter.h
+++ b/Source/Core/Common/x64Emitter.h
@@ -5,9 +5,12 @@
 
 #pragma once
 
+#include <array>
+#include <concepts>
 #include <cstddef>
 #include <cstring>
 #include <functional>
+#include <optional>
 #include <tuple>
 #include <type_traits>
 
@@ -15,6 +18,7 @@
 #include "Common/BitSet.h"
 #include "Common/CodeBlock.h"
 #include "Common/CommonTypes.h"
+#include "Common/SmallVector.h"
 #include "Common/x64ABI.h"
 
 namespace Gen
@@ -226,6 +230,39 @@ struct OpArg
   }
 
 private:
+  constexpr std::optional<X64Reg> GetBaseReg() const
+  {
+    switch (scale)
+    {
+    case SCALE_NONE:
+    case SCALE_1:
+    case SCALE_2:
+    case SCALE_4:
+    case SCALE_8:
+    case SCALE_ATREG:
+      return static_cast<X64Reg>(offsetOrBaseReg);
+    default:
+      return std::nullopt;
+    }
+  }
+
+  constexpr std::optional<X64Reg> GetIndexReg() const
+  {
+    switch (scale)
+    {
+    case SCALE_1:
+    case SCALE_2:
+    case SCALE_4:
+    case SCALE_8:
+    case SCALE_NOBASE_2:
+    case SCALE_NOBASE_4:
+    case SCALE_NOBASE_8:
+      return static_cast<X64Reg>(indexReg);
+    default:
+      return std::nullopt;
+    }
+  }
+
   void WriteREX(XEmitter* emit, int opBits, int bits, int customOp = -1) const;
   void WriteVEX(XEmitter* emit, X64Reg regOp1, X64Reg regOp2, int L, int pp, int mmmmm,
                 int W = 0) const;
@@ -327,6 +364,13 @@ class XEmitter
 {
   friend struct OpArg;  // for Write8 etc
 private:
+  struct RegisterMove
+  {
+    int bits;
+    X64Reg destination;
+    OpArg source;
+  };
+
   // Pointer to memory where code will be emitted to.
   u8* code = nullptr;
 
@@ -377,6 +421,11 @@ private:
   void ABI_CalculateFrameSize(BitSet32 mask, size_t rsp_alignment, size_t needed_frame_size,
                               size_t* shadowp, size_t* subtractionp, size_t* xmm_offsetp);
 
+  // This function solves the "parallel moves" problem that's common in compilers.
+  // The arguments are mutated!
+  void ParallelMoves(RegisterMove* begin, RegisterMove* end, std::array<u8, 16>* source_reg_uses,
+                     std::array<u8, 16>* destination_reg_uses);
+
 protected:
   void Write8(u8 value);
   void Write16(u16 value);
@@ -988,10 +1037,10 @@ public:
   void RDTSC();
 
   // Utility functions
-  // The difference between this and CALL is that this aligns the stack
-  // where appropriate.
+
+  // Calls a function without setting up arguments or aligning the stack.
   template <typename FunctionPointer>
-  void ABI_CallFunction(FunctionPointer func)
+  void QuickCallFunction(FunctionPointer func)
   {
     static_assert(std::is_pointer<FunctionPointer>() &&
                       std::is_function<std::remove_pointer_t<FunctionPointer>>(),
@@ -1013,167 +1062,145 @@ public:
     }
   }
 
-  template <typename FunctionPointer>
-  void ABI_CallFunctionC16(FunctionPointer func, u16 param1)
+  struct CallFunctionArg
   {
-    MOV(32, R(ABI_PARAM1), Imm32(param1));
-    ABI_CallFunction(func);
-  }
+    template <std::integral T>
+    CallFunctionArg(T imm)
+        : bits(sizeof(T) > 4 ? 64 : 32),
+          op_arg(sizeof(T) > 4 ? Imm64(imm) : Imm32(std::is_signed_v<T> ? s32(imm) : u32(imm)))
+    {
+    }
 
-  template <typename FunctionPointer>
-  void ABI_CallFunctionCC16(FunctionPointer func, u32 param1, u16 param2)
-  {
-    MOV(32, R(ABI_PARAM1), Imm32(param1));
-    MOV(32, R(ABI_PARAM2), Imm32(param2));
-    ABI_CallFunction(func);
-  }
+    CallFunctionArg(const void* imm) : bits(64), op_arg(Imm64(reinterpret_cast<u64>(imm))) {}
 
-  template <typename FunctionPointer>
-  void ABI_CallFunctionC(FunctionPointer func, u32 param1)
-  {
-    MOV(32, R(ABI_PARAM1), Imm32(param1));
-    ABI_CallFunction(func);
-  }
+    CallFunctionArg(int bits_, const OpArg& op_arg_) : bits(bits_), op_arg(op_arg_) {}
 
-  template <typename FunctionPointer>
-  void ABI_CallFunctionCC(FunctionPointer func, u32 param1, u32 param2)
-  {
-    MOV(32, R(ABI_PARAM1), Imm32(param1));
-    MOV(32, R(ABI_PARAM2), Imm32(param2));
-    ABI_CallFunction(func);
-  }
+    CallFunctionArg(int bits_, const X64Reg reg) : bits(bits_), op_arg(R(reg)) {}
 
-  template <typename FunctionPointer>
-  void ABI_CallFunctionCP(FunctionPointer func, u32 param1, const void* param2)
-  {
-    MOV(32, R(ABI_PARAM1), Imm32(param1));
-    MOV(64, R(ABI_PARAM2), Imm64(reinterpret_cast<u64>(param2)));
-    ABI_CallFunction(func);
-  }
+    int bits;
+    OpArg op_arg;
+  };
 
-  template <typename FunctionPointer>
-  void ABI_CallFunctionCCC(FunctionPointer func, u32 param1, u32 param2, u32 param3)
+  // Calls a function using the given arguments. This doesn't adjust the stack; you can do that
+  // using ABI_PushRegistersAndAdjustStack and ABI_PopRegistersAndAdjustStack.
+  template <typename FuncRet, typename... FuncArgs, std::convertible_to<CallFunctionArg>... Args>
+  void ABI_CallFunction(FuncRet (*func)(FuncArgs...), Args... args)
   {
-    MOV(32, R(ABI_PARAM1), Imm32(param1));
-    MOV(32, R(ABI_PARAM2), Imm32(param2));
-    MOV(32, R(ABI_PARAM3), Imm32(param3));
-    ABI_CallFunction(func);
-  }
+    static_assert(sizeof...(FuncArgs) == sizeof...(Args), "Wrong number of arguments");
+    static_assert(sizeof...(FuncArgs) <= ABI_PARAMS.size(),
+                  "Passing arguments on the stack is not supported");
 
-  template <typename FunctionPointer>
-  void ABI_CallFunctionCCP(FunctionPointer func, u32 param1, u32 param2, const void* param3)
-  {
-    MOV(32, R(ABI_PARAM1), Imm32(param1));
-    MOV(32, R(ABI_PARAM2), Imm32(param2));
-    MOV(64, R(ABI_PARAM3), Imm64(reinterpret_cast<u64>(param3)));
-    ABI_CallFunction(func);
-  }
+    if constexpr (!std::is_void_v<FuncRet>)
+      static_assert(sizeof(FuncRet) <= 8, "Large return types are not supported");
 
-  template <typename FunctionPointer>
-  void ABI_CallFunctionCCCP(FunctionPointer func, u32 param1, u32 param2, u32 param3,
-                            const void* param4)
-  {
-    MOV(32, R(ABI_PARAM1), Imm32(param1));
-    MOV(32, R(ABI_PARAM2), Imm32(param2));
-    MOV(32, R(ABI_PARAM3), Imm32(param3));
-    MOV(64, R(ABI_PARAM4), Imm64(reinterpret_cast<u64>(param4)));
-    ABI_CallFunction(func);
-  }
+    std::array<u8, 16> source_reg_uses{};
+    std::array<u8, 16> destination_reg_uses{};
 
-  template <typename FunctionPointer>
-  void ABI_CallFunctionP(FunctionPointer func, const void* param1)
-  {
-    MOV(64, R(ABI_PARAM1), Imm64(reinterpret_cast<u64>(param1)));
-    ABI_CallFunction(func);
-  }
+    auto check_argument = [&](const CallFunctionArg& arg) {
+      if (const std::optional<X64Reg> base_reg = arg.op_arg.GetBaseReg())
+        source_reg_uses[*base_reg]++;
+      if (const std::optional<X64Reg> index_reg = arg.op_arg.GetIndexReg())
+        source_reg_uses[*index_reg]++;
+    };
 
-  template <typename FunctionPointer>
-  void ABI_CallFunctionPP(FunctionPointer func, const void* param1, const void* param2)
-  {
-    MOV(64, R(ABI_PARAM1), Imm64(reinterpret_cast<u64>(param1)));
-    MOV(64, R(ABI_PARAM2), Imm64(reinterpret_cast<u64>(param2)));
-    ABI_CallFunction(func);
-  }
+    (check_argument(args), ...);
 
-  template <typename FunctionPointer>
-  void ABI_CallFunctionPC(FunctionPointer func, const void* param1, u32 param2)
-  {
-    MOV(64, R(ABI_PARAM1), Imm64(reinterpret_cast<u64>(param1)));
-    MOV(32, R(ABI_PARAM2), Imm32(param2));
-    ABI_CallFunction(func);
-  }
+    {
+      Common::SmallVector<RegisterMove, sizeof...(Args)> pending_moves;
 
-  template <typename FunctionPointer>
-  void ABI_CallFunctionPPC(FunctionPointer func, const void* param1, const void* param2, u32 param3)
-  {
-    MOV(64, R(ABI_PARAM1), Imm64(reinterpret_cast<u64>(param1)));
-    MOV(64, R(ABI_PARAM2), Imm64(reinterpret_cast<u64>(param2)));
-    MOV(32, R(ABI_PARAM3), Imm32(param3));
-    ABI_CallFunction(func);
-  }
+      size_t i = 0;
 
-  // Pass a register as a parameter.
-  template <typename FunctionPointer>
-  void ABI_CallFunctionR(FunctionPointer func, X64Reg reg1)
-  {
-    if (reg1 != ABI_PARAM1)
-      MOV(32, R(ABI_PARAM1), R(reg1));
-    ABI_CallFunction(func);
-  }
+      auto handle_non_imm_argument = [&](const CallFunctionArg& arg) {
+        if (!arg.op_arg.IsImm())
+        {
+          // When types that are 32 bits or smaller are stored in a register, bits 32-63 of the
+          // register can contain garbage. However, the System V ABI doesn't specify any rules
+          // for bits 8-31 and 16-31 for char and short respectively. (It does specify that _Bool
+          // must contain zeroes in bits 1-7 but can contain garbage in bits 8-31.) Apple's ABI
+          // documentation says that zero/sign extending is required for char and short, and GCC and
+          // Clang seem to assume that it's required. The situation on Windows is currently unknown.
+          // Let's assume that it's required on all platforms.
+          //
+          // TODO: Use sign extension instead of zero extension if the relevant type is signed.
+          const bool zero_extend = arg.bits < 32;
 
-  // Pass a pointer and register as a parameter.
-  template <typename FunctionPointer>
-  void ABI_CallFunctionPR(FunctionPointer func, const void* ptr, X64Reg reg1)
-  {
-    if (reg1 != ABI_PARAM2)
-      MOV(64, R(ABI_PARAM2), R(reg1));
-    MOV(64, R(ABI_PARAM1), Imm64(reinterpret_cast<u64>(ptr)));
-    ABI_CallFunction(func);
-  }
+          const X64Reg destination_reg = ABI_PARAMS[i];
 
-  // Pass two registers as parameters.
-  template <typename FunctionPointer>
-  void ABI_CallFunctionRR(FunctionPointer func, X64Reg reg1, X64Reg reg2)
-  {
-    MOVTwo(64, ABI_PARAM1, reg1, 0, ABI_PARAM2, reg2);
-    ABI_CallFunction(func);
-  }
+          const auto destination_reg_uses_minus_this_source = [&] {
+            return source_reg_uses[destination_reg] - (arg.op_arg.GetBaseReg() == destination_reg) -
+                   (arg.op_arg.GetIndexReg() == destination_reg);
+          };
 
-  // Pass a pointer and two registers as parameters.
-  template <typename FunctionPointer>
-  void ABI_CallFunctionPRR(FunctionPointer func, const void* ptr, X64Reg reg1, X64Reg reg2)
-  {
-    MOVTwo(64, ABI_PARAM2, reg1, 0, ABI_PARAM3, reg2);
-    MOV(64, R(ABI_PARAM1), Imm64(reinterpret_cast<u64>(ptr)));
-    ABI_CallFunction(func);
-  }
+          if (arg.op_arg.IsSimpleReg(destination_reg) && !zero_extend)
+          {
+            // The value is already in the right register.
+            destination_reg_uses[destination_reg]++;
+            source_reg_uses[destination_reg]--;
+          }
+          else if (destination_reg_uses_minus_this_source() == 0)
+          {
+            // The destination register isn't used as the source of another move.
+            // We can go ahead and do the move right away.
+            if (zero_extend)
+              MOVZX(32, arg.bits, destination_reg, arg.op_arg);
+            else
+              MOV(arg.bits, R(destination_reg), arg.op_arg);
 
-  template <typename FunctionPointer>
-  void ABI_CallFunctionAC(int bits, FunctionPointer func, const Gen::OpArg& arg1, u32 param2)
-  {
-    if (!arg1.IsSimpleReg(ABI_PARAM1))
-      MOV(bits, R(ABI_PARAM1), arg1);
-    MOV(32, R(ABI_PARAM2), Imm32(param2));
-    ABI_CallFunction(func);
-  }
+            destination_reg_uses[destination_reg]++;
+            if (const std::optional<X64Reg> base_reg = arg.op_arg.GetBaseReg())
+              source_reg_uses[*base_reg]--;
+            if (const std::optional<X64Reg> index_reg = arg.op_arg.GetIndexReg())
+              source_reg_uses[*index_reg]--;
+          }
+          else
+          {
+            // The destination register is used as the source of a move we haven't gotten to yet.
+            // Let's record that we need to deal with this move later.
+            pending_moves.emplace_back(arg.bits, destination_reg, arg.op_arg);
+          }
+        }
 
-  template <typename FunctionPointer>
-  void ABI_CallFunctionPAC(int bits, FunctionPointer func, const void* ptr1, const Gen::OpArg& arg2,
-                           u32 param3)
-  {
-    if (!arg2.IsSimpleReg(ABI_PARAM2))
-      MOV(bits, R(ABI_PARAM2), arg2);
-    MOV(32, R(ABI_PARAM3), Imm32(param3));
-    MOV(64, R(ABI_PARAM1), Imm64(reinterpret_cast<u64>(ptr1)));
-    ABI_CallFunction(func);
-  }
+        ++i;
+      };
 
-  template <typename FunctionPointer>
-  void ABI_CallFunctionA(int bits, FunctionPointer func, const Gen::OpArg& arg1)
-  {
-    if (!arg1.IsSimpleReg(ABI_PARAM1))
-      MOV(bits, R(ABI_PARAM1), arg1);
-    ABI_CallFunction(func);
+      (handle_non_imm_argument(args), ...);
+
+      if (!pending_moves.empty())
+      {
+        ParallelMoves(pending_moves.data(), pending_moves.data() + pending_moves.size(),
+                      &source_reg_uses, &destination_reg_uses);
+      }
+    }
+
+    {
+      size_t i = 0;
+
+      auto handle_imm_argument = [&](const CallFunctionArg& arg) {
+        switch (arg.op_arg.scale)
+        {
+        case SCALE_IMM8:
+          // TODO: Use sign extension instead of zero extension if the relevant type is signed.
+          MOV(32, R(ABI_PARAMS[i]), Imm32(arg.op_arg.Imm8()));
+          break;
+        case SCALE_IMM16:
+          // TODO: Use sign extension instead of zero extension if the relevant type is signed.
+          MOV(32, R(ABI_PARAMS[i]), Imm32(arg.op_arg.Imm16()));
+          break;
+        case SCALE_IMM32:
+        case SCALE_IMM64:
+          MOV(arg.bits, R(ABI_PARAMS[i]), arg.op_arg);
+          break;
+        default:
+          break;
+        }
+
+        ++i;
+      };
+
+      (handle_imm_argument(args), ...);
+    }
+
+    QuickCallFunction(func);
   }
 
   // Helper method for ABI functions related to calling functions. May be used by itself as well.
@@ -1192,17 +1219,18 @@ public:
   // Unfortunately, calling operator() directly is undefined behavior in C++
   // (this method might be a thunk in the case of multi-inheritance) so we
   // have to go through a trampoline function.
-  template <typename T, typename... Args>
-  static T CallLambdaTrampoline(const std::function<T(Args...)>* f, Args... args)
+  template <typename FuncRet, typename... FuncArgs>
+  static FuncRet CallLambdaTrampoline(const std::function<FuncRet(FuncArgs...)>* f,
+                                      FuncArgs... args)
   {
     return (*f)(args...);
   }
 
-  template <typename T, typename... Args>
-  void ABI_CallLambdaPC(const std::function<T(Args...)>* f, void* p1, u32 p2)
+  template <typename FuncRet, typename... FuncArgs, std::convertible_to<CallFunctionArg>... Args>
+  void ABI_CallLambda(const std::function<FuncRet(FuncArgs...)>* f, Args... args)
   {
-    auto trampoline = &XEmitter::CallLambdaTrampoline<T, Args...>;
-    ABI_CallFunctionPPC(trampoline, reinterpret_cast<const void*>(f), p1, p2);
+    auto trampoline = &XEmitter::CallLambdaTrampoline<FuncRet, FuncArgs...>;
+    ABI_CallFunction(trampoline, reinterpret_cast<const void*>(f), args...);
   }
 };  // class XEmitter
 
diff --git a/Source/Core/Core/DSP/Jit/x64/DSPEmitter.cpp b/Source/Core/Core/DSP/Jit/x64/DSPEmitter.cpp
index f84a85b0679..c4826910881 100644
--- a/Source/Core/Core/DSP/Jit/x64/DSPEmitter.cpp
+++ b/Source/Core/Core/DSP/Jit/x64/DSPEmitter.cpp
@@ -115,7 +115,7 @@ void DSPEmitter::checkExceptions(u32 retval)
 
   DSPJitRegCache c(m_gpr);
   m_gpr.SaveRegs();
-  ABI_CallFunctionP(CheckExceptionsThunk, &m_dsp_core);
+  ABI_CallFunction(CheckExceptionsThunk, &m_dsp_core);
   TEST(32, R(ABI_RETURN), R(ABI_RETURN));
   FixupBranch skip_return = J_CC(CC_Z, Jump::Short);
   MOV(32, R(EAX), Imm32(retval));
@@ -157,7 +157,7 @@ void DSPEmitter::FallBackToInterpreter(UDSPInstruction inst)
 
   m_gpr.PushRegs();
   ASSERT_MSG(DSPLLE, interpreter_function != nullptr, "No function for {:04x}", inst);
-  ABI_CallFunctionPC(FallbackThunk, &m_dsp_core.GetInterpreter(), inst);
+  ABI_CallFunction(FallbackThunk, &m_dsp_core.GetInterpreter(), inst);
   m_gpr.PopRegs();
 }
 
@@ -190,7 +190,7 @@ void DSPEmitter::EmitInstruction(UDSPInstruction inst)
     {
       // Fall back to interpreter
       m_gpr.PushRegs();
-      ABI_CallFunctionPC(FallbackExtThunk, &m_dsp_core.GetInterpreter(), inst);
+      ABI_CallFunction(FallbackExtThunk, &m_dsp_core.GetInterpreter(), inst);
       m_gpr.PopRegs();
       INFO_LOG_FMT(DSPLLE, "Instruction not JITed(ext part): {:04x}", inst);
       ext_is_jit = false;
@@ -217,7 +217,7 @@ void DSPEmitter::EmitInstruction(UDSPInstruction inst)
       // need to call the online cleanup function because
       // the writeBackLog gets populated at runtime
       m_gpr.PushRegs();
-      ABI_CallFunctionP(ApplyWriteBackLogThunk, &m_dsp_core.GetInterpreter());
+      ABI_CallFunction(ApplyWriteBackLogThunk, &m_dsp_core.GetInterpreter());
       m_gpr.PopRegs();
     }
     else
@@ -420,8 +420,7 @@ void DSPEmitter::CompileCurrent(DSPEmitter& emitter)
 const u8* DSPEmitter::CompileStub()
 {
   const u8* entryPoint = AlignCode16();
-  MOV(64, R(ABI_PARAM1), Imm64(reinterpret_cast<u64>(this)));
-  ABI_CallFunction(CompileCurrent);
+  ABI_CallFunction(CompileCurrent, this);
   XOR(32, R(EAX), R(EAX));  // Return 0 cycles executed
   JMP(m_return_dispatcher);
   return entryPoint;
diff --git a/Source/Core/Core/DSP/Jit/x64/DSPJitRegCache.cpp b/Source/Core/Core/DSP/Jit/x64/DSPJitRegCache.cpp
index 47a011e9b47..f09f0de9aa0 100644
--- a/Source/Core/Core/DSP/Jit/x64/DSPJitRegCache.cpp
+++ b/Source/Core/Core/DSP/Jit/x64/DSPJitRegCache.cpp
@@ -501,11 +501,6 @@ void DSPJitRegCache::PopRegs()
   }
 }
 
-X64Reg DSPJitRegCache::MakeABICallSafe(X64Reg reg)
-{
-  return reg;
-}
-
 void DSPJitRegCache::MovToHostReg(size_t reg, X64Reg host_reg, bool load)
 {
   ASSERT_MSG(DSPLLE, reg < m_regs.size(), "bad register name {}", reg);
diff --git a/Source/Core/Core/DSP/Jit/x64/DSPJitRegCache.h b/Source/Core/Core/DSP/Jit/x64/DSPJitRegCache.h
index 24bc45b2e62..73c3ecdbc35 100644
--- a/Source/Core/Core/DSP/Jit/x64/DSPJitRegCache.h
+++ b/Source/Core/Core/DSP/Jit/x64/DSPJitRegCache.h
@@ -108,10 +108,6 @@ public:
   void PushRegs();  // Save registers before ABI call
   void PopRegs();   // Restore registers after ABI call
 
-  // Returns a register with the same contents as reg that is safe
-  // to use through saveStaticRegs and for ABI-calls
-  Gen::X64Reg MakeABICallSafe(Gen::X64Reg reg);
-
   // Gives no SCALE_RIP with abs(offset) >= 0x80000000
   // 32/64 bit writes allowed when the register has a _64 or _32 suffix
   // only 16 bit writes allowed without any suffix.
diff --git a/Source/Core/Core/DSP/Jit/x64/DSPJitUtil.cpp b/Source/Core/Core/DSP/Jit/x64/DSPJitUtil.cpp
index 622d080fe1c..c6864d0a04d 100644
--- a/Source/Core/Core/DSP/Jit/x64/DSPJitUtil.cpp
+++ b/Source/Core/Core/DSP/Jit/x64/DSPJitUtil.cpp
@@ -495,10 +495,9 @@ void DSPEmitter::dmem_write(X64Reg value)
   //	else if (saddr == 0xf)
   SetJumpTarget(ifx);
   DSPJitRegCache c(m_gpr);
-  X64Reg abisafereg = m_gpr.MakeABICallSafe(value);
-  MOVZX(32, 16, abisafereg, R(abisafereg));
   m_gpr.PushRegs();
-  ABI_CallFunctionPRR(WriteIFXRegisterHelper, this, EAX, abisafereg);
+  ABI_CallFunction(WriteIFXRegisterHelper, this, CallFunctionArg(32, EAX),
+                   CallFunctionArg(16, value));
   m_gpr.PopRegs();
   m_gpr.FlushRegs(c);
   SetJumpTarget(end);
@@ -515,10 +514,8 @@ void DSPEmitter::dmem_write_imm(u16 address, X64Reg value)
 
   case 0xf:  // Fxxx HW regs
   {
-    MOV(16, R(EAX), Imm16(address));
-    X64Reg abisafereg = m_gpr.MakeABICallSafe(value);
     m_gpr.PushRegs();
-    ABI_CallFunctionPRR(WriteIFXRegisterHelper, this, EAX, abisafereg);
+    ABI_CallFunction(WriteIFXRegisterHelper, this, address, CallFunctionArg(32, value));
     m_gpr.PopRegs();
     break;
   }
@@ -581,9 +578,8 @@ void DSPEmitter::dmem_read(X64Reg address)
   //	else if (saddr == 0xf)
   //		return gdsp_ifx_read(addr);
   DSPJitRegCache c(m_gpr);
-  X64Reg abisafereg = m_gpr.MakeABICallSafe(address);
   m_gpr.PushRegs();
-  ABI_CallFunctionPR(ReadIFXRegisterHelper, this, abisafereg);
+  ABI_CallFunction(ReadIFXRegisterHelper, this, CallFunctionArg(32, address));
   m_gpr.PopRegs();
   m_gpr.FlushRegs(c);
   SetJumpTarget(end);
@@ -607,7 +603,7 @@ void DSPEmitter::dmem_read_imm(u16 address)
   case 0xf:  // Fxxx HW regs
   {
     m_gpr.PushRegs();
-    ABI_CallFunctionPC(ReadIFXRegisterHelper, this, address);
+    ABI_CallFunction(ReadIFXRegisterHelper, this, address);
     m_gpr.PopRegs();
     break;
   }
diff --git a/Source/Core/Core/PowerPC/Jit64/Jit.cpp b/Source/Core/Core/PowerPC/Jit64/Jit.cpp
index 1cdaf8c55ac..812fcc7c644 100644
--- a/Source/Core/Core/PowerPC/Jit64/Jit.cpp
+++ b/Source/Core/Core/PowerPC/Jit64/Jit.cpp
@@ -363,7 +363,7 @@ void Jit64::FallBackToInterpreter(UGeckoInstruction inst)
 
   Interpreter::Instruction instr = Interpreter::GetInterpreterOp(inst);
   ABI_PushRegistersAndAdjustStack({}, 0);
-  ABI_CallFunctionPC(instr, &m_system.GetInterpreter(), inst.hex);
+  ABI_CallFunction(instr, &m_system.GetInterpreter(), inst.hex);
   ABI_PopRegistersAndAdjustStack({}, 0);
 
   // If the instruction wrote to any registers which were marked as discarded,
@@ -420,7 +420,7 @@ void Jit64::HLEFunction(u32 hook_index)
   gpr.Flush();
   fpr.Flush();
   ABI_PushRegistersAndAdjustStack({}, 0);
-  ABI_CallFunctionCCP(HLE::ExecuteFromJIT, js.compilerPC, hook_index, &m_system);
+  ABI_CallFunction(HLE::ExecuteFromJIT, js.compilerPC, hook_index, &m_system);
   ABI_PopRegistersAndAdjustStack({}, 0);
 }
 
@@ -463,7 +463,7 @@ bool Jit64::Cleanup()
     CMP(64, R(RSCRATCH), Imm32(GPFifo::GATHER_PIPE_SIZE));
     FixupBranch exit = J_CC(CC_L);
     ABI_PushRegistersAndAdjustStack({}, 0);
-    ABI_CallFunctionP(GPFifo::UpdateGatherPipe, &m_system.GetGPFifo());
+    ABI_CallFunction(GPFifo::UpdateGatherPipe, &m_system.GetGPFifo());
     ABI_PopRegistersAndAdjustStack({}, 0);
     SetJumpTarget(exit);
     did_something = true;
@@ -472,8 +472,8 @@ bool Jit64::Cleanup()
   if (m_ppc_state.feature_flags & FEATURE_FLAG_PERFMON)
   {
     ABI_PushRegistersAndAdjustStack({}, 0);
-    ABI_CallFunctionCCCP(PowerPC::UpdatePerformanceMonitor, js.downcountAmount, js.numLoadStoreInst,
-                         js.numFloatingPointInst, &m_ppc_state);
+    ABI_CallFunction(PowerPC::UpdatePerformanceMonitor, js.downcountAmount, js.numLoadStoreInst,
+                     js.numFloatingPointInst, &m_ppc_state);
     ABI_PopRegistersAndAdjustStack({}, 0);
     did_something = true;
   }
@@ -481,8 +481,8 @@ bool Jit64::Cleanup()
   if (IsProfilingEnabled())
   {
     ABI_PushRegistersAndAdjustStack({}, 0);
-    ABI_CallFunctionPC(&JitBlock::ProfileData::EndProfiling, js.curBlock->profile_data.get(),
-                       js.downcountAmount);
+    ABI_CallFunction(&JitBlock::ProfileData::EndProfiling, js.curBlock->profile_data.get(),
+                     js.downcountAmount);
     ABI_PopRegistersAndAdjustStack({}, 0);
     did_something = true;
   }
@@ -667,7 +667,7 @@ void Jit64::WriteRfiExitDestInRSCRATCH()
   MOV(32, PPCSTATE(npc), R(RSCRATCH));
   Cleanup();
   ABI_PushRegistersAndAdjustStack({}, 0);
-  ABI_CallFunctionP(PowerPC::CheckExceptionsFromJIT, &m_system.GetPowerPC());
+  ABI_CallFunction(PowerPC::CheckExceptionsFromJIT, &m_system.GetPowerPC());
   ABI_PopRegistersAndAdjustStack({}, 0);
   EmitUpdateMembase();
   SUB(32, PPCSTATE(downcount), Imm32(js.downcountAmount));
@@ -689,7 +689,7 @@ void Jit64::WriteExceptionExit()
   MOV(32, R(RSCRATCH), PPCSTATE(pc));
   MOV(32, PPCSTATE(npc), R(RSCRATCH));
   ABI_PushRegistersAndAdjustStack({}, 0);
-  ABI_CallFunctionP(PowerPC::CheckExceptionsFromJIT, &m_system.GetPowerPC());
+  ABI_CallFunction(PowerPC::CheckExceptionsFromJIT, &m_system.GetPowerPC());
   ABI_PopRegistersAndAdjustStack({}, 0);
   EmitUpdateMembase();
   SUB(32, PPCSTATE(downcount), Imm32(js.downcountAmount));
@@ -702,7 +702,7 @@ void Jit64::WriteExternalExceptionExit()
   MOV(32, R(RSCRATCH), PPCSTATE(pc));
   MOV(32, PPCSTATE(npc), R(RSCRATCH));
   ABI_PushRegistersAndAdjustStack({}, 0);
-  ABI_CallFunctionP(PowerPC::CheckExternalExceptionsFromJIT, &m_system.GetPowerPC());
+  ABI_CallFunction(PowerPC::CheckExternalExceptionsFromJIT, &m_system.GetPowerPC());
   ABI_PopRegistersAndAdjustStack({}, 0);
   EmitUpdateMembase();
   SUB(32, PPCSTATE(downcount), Imm32(js.downcountAmount));
@@ -908,13 +908,13 @@ bool Jit64::DoJit(u32 em_address, JitBlock* b, u32 nextPC)
   if (m_im_here_debug)
   {
     ABI_PushRegistersAndAdjustStack({}, 0);
-    ABI_CallFunctionP(ImHere, this);
+    ABI_CallFunction(ImHere, this);
     ABI_PopRegistersAndAdjustStack({}, 0);
   }
 
   // Conditionally add profiling code.
   if (IsProfilingEnabled())
-    ABI_CallFunctionP(&JitBlock::ProfileData::BeginProfiling, b->profile_data.get());
+    ABI_CallFunction(&JitBlock::ProfileData::BeginProfiling, b->profile_data.get());
 
 #if defined(_DEBUG) || defined(DEBUGFAST) || defined(NAN_CHECK)
   // should help logged stack-traces become more accurate
@@ -946,8 +946,8 @@ bool Jit64::DoJit(u32 em_address, JitBlock* b, u32 nextPC)
       const u8* target = GetCodePtr();
       MOV(32, PPCSTATE(pc), Imm32(js.blockStart));
       ABI_PushRegistersAndAdjustStack({}, 0);
-      ABI_CallFunctionPC(JitInterface::CompileExceptionCheckFromJIT, &m_system.GetJitInterface(),
-                         static_cast<u32>(JitInterface::ExceptionType::PairedQuantize));
+      ABI_CallFunction(JitInterface::CompileExceptionCheckFromJIT, &m_system.GetJitInterface(),
+                       static_cast<u32>(JitInterface::ExceptionType::PairedQuantize));
       ABI_PopRegistersAndAdjustStack({}, 0);
       JMP(asm_routines.dispatcher_no_check);
       SwitchToNearCode();
@@ -1003,7 +1003,7 @@ bool Jit64::DoJit(u32 em_address, JitBlock* b, u32 nextPC)
         js.mustCheckFifo = false;
         BitSet32 registersInUse = CallerSavedRegistersInUse();
         ABI_PushRegistersAndAdjustStack(registersInUse, 0);
-        ABI_CallFunctionP(GPFifo::FastCheckGatherPipe, &m_system.GetGPFifo());
+        ABI_CallFunction(GPFifo::FastCheckGatherPipe, &m_system.GetGPFifo());
         ABI_PopRegistersAndAdjustStack(registersInUse, 0);
         gatherPipeIntCheck = true;
       }
@@ -1068,7 +1068,7 @@ bool Jit64::DoJit(u32 em_address, JitBlock* b, u32 nextPC)
 
         MOV(32, PPCSTATE(pc), Imm32(op.address));
         ABI_PushRegistersAndAdjustStack({}, 0);
-        ABI_CallFunctionP(PowerPC::CheckAndHandleBreakPointsFromJIT, &power_pc);
+        ABI_CallFunction(PowerPC::CheckAndHandleBreakPointsFromJIT, &power_pc);
         ABI_PopRegistersAndAdjustStack({}, 0);
         MOV(64, R(RSCRATCH), ImmPtr(cpu.GetStatePtr()));
         CMP(32, MatR(RSCRATCH), Imm32(Common::ToUnderlying(CPU::State::Running)));
@@ -1328,8 +1328,8 @@ void Jit64::IntializeSpeculativeConstants()
         target = GetCodePtr();
         MOV(32, PPCSTATE(pc), Imm32(js.blockStart));
         ABI_PushRegistersAndAdjustStack({}, 0);
-        ABI_CallFunctionPC(JitInterface::CompileExceptionCheckFromJIT, &m_system.GetJitInterface(),
-                           static_cast<u32>(JitInterface::ExceptionType::SpeculativeConstants));
+        ABI_CallFunction(JitInterface::CompileExceptionCheckFromJIT, &m_system.GetJitInterface(),
+                         static_cast<u32>(JitInterface::ExceptionType::SpeculativeConstants));
         ABI_PopRegistersAndAdjustStack({}, 0);
         JMP(asm_routines.dispatcher_no_check);
         SwitchToNearCode();
diff --git a/Source/Core/Core/PowerPC/Jit64/JitAsm.cpp b/Source/Core/Core/PowerPC/Jit64/JitAsm.cpp
index eea2e75b0c3..7e0b0aac623 100644
--- a/Source/Core/Core/PowerPC/Jit64/JitAsm.cpp
+++ b/Source/Core/Core/PowerPC/Jit64/JitAsm.cpp
@@ -190,8 +190,7 @@ void Jit64AsmRoutineManager::Generate()
   {
     // Ok, no block, let's call the slow dispatcher
     ABI_PushRegistersAndAdjustStack({}, 0);
-    MOV(64, R(ABI_PARAM1), Imm64(reinterpret_cast<u64>(&m_jit)));
-    ABI_CallFunction(JitBase::Dispatch);
+    ABI_CallFunction(JitBase::Dispatch, &m_jit);
     ABI_PopRegistersAndAdjustStack({}, 0);
 
     TEST(64, R(ABI_RETURN), R(ABI_RETURN));
@@ -210,9 +209,7 @@ void Jit64AsmRoutineManager::Generate()
   ResetStack(*this);
 
   ABI_PushRegistersAndAdjustStack({}, 0);
-  MOV(64, R(ABI_PARAM1), Imm64(reinterpret_cast<u64>(&m_jit)));
-  MOV(32, R(ABI_PARAM2), PPCSTATE(pc));
-  ABI_CallFunction(JitTrampoline);
+  ABI_CallFunction(JitTrampoline, &m_jit, CallFunctionArg(32, PPCSTATE(pc)));
   ABI_PopRegistersAndAdjustStack({}, 0);
 
   // If jitting triggered an ISI exception, MSR.DR may have changed
diff --git a/Source/Core/Core/PowerPC/Jit64/Jit_Branch.cpp b/Source/Core/Core/PowerPC/Jit64/Jit_Branch.cpp
index bd611e2c7b5..522221b4bd3 100644
--- a/Source/Core/Core/PowerPC/Jit64/Jit_Branch.cpp
+++ b/Source/Core/Core/PowerPC/Jit64/Jit_Branch.cpp
@@ -80,15 +80,12 @@ void Jit64::WriteBranchWatch(u32 origin, u32 destination, UGeckoInstruction inst
   SetJumpTarget(branch_in);
 
   ABI_PushRegistersAndAdjustStack(caller_save, 0);
-  // Some call sites have an optimization to use ABI_PARAM1 as a scratch register.
-  if (reg_a != ABI_PARAM1)
-    MOV(64, R(ABI_PARAM1), R(reg_a));
-  MOV(64, R(ABI_PARAM2), Imm64(Core::FakeBranchWatchCollectionKey{origin, destination}));
-  MOV(32, R(ABI_PARAM3), Imm32(inst.hex));
-  ABI_CallFunction(m_ppc_state.msr.IR ? (condition ? &Core::BranchWatch::HitVirtualTrue_fk :
-                                                     &Core::BranchWatch::HitVirtualFalse_fk) :
-                                        (condition ? &Core::BranchWatch::HitPhysicalTrue_fk :
-                                                     &Core::BranchWatch::HitPhysicalFalse_fk));
+  const auto function = m_ppc_state.msr.IR ? (condition ? &Core::BranchWatch::HitVirtualTrue_fk :
+                                                          &Core::BranchWatch::HitVirtualFalse_fk) :
+                                             (condition ? &Core::BranchWatch::HitPhysicalTrue_fk :
+                                                          &Core::BranchWatch::HitPhysicalFalse_fk);
+  ABI_CallFunction(function, CallFunctionArg(64, reg_a),
+                   u64(Core::FakeBranchWatchCollectionKey{origin, destination}), inst.hex);
   ABI_PopRegistersAndAdjustStack(caller_save, 0);
 
   FixupBranch branch_out = J(Jump::Near);
@@ -110,18 +107,11 @@ void Jit64::WriteBranchWatchDestInRSCRATCH(u32 origin, UGeckoInstruction inst, X
   SwitchToFarCode();
   SetJumpTarget(branch_in);
 
-  // Assert RSCRATCH won't be clobbered before it is moved from.
-  static_assert(ABI_PARAM1 != RSCRATCH);
-
   ABI_PushRegistersAndAdjustStack(caller_save, 0);
-  // Some call sites have an optimization to use ABI_PARAM1 as a scratch register.
-  if (reg_a != ABI_PARAM1)
-    MOV(64, R(ABI_PARAM1), R(reg_a));
-  MOV(32, R(ABI_PARAM3), R(RSCRATCH));
-  MOV(32, R(ABI_PARAM2), Imm32(origin));
-  MOV(32, R(ABI_PARAM4), Imm32(inst.hex));
-  ABI_CallFunction(m_ppc_state.msr.IR ? &Core::BranchWatch::HitVirtualTrue :
-                                        &Core::BranchWatch::HitPhysicalTrue);
+  const auto function =
+      m_ppc_state.msr.IR ? &Core::BranchWatch::HitVirtualTrue : &Core::BranchWatch::HitPhysicalTrue;
+  ABI_CallFunction(function, CallFunctionArg(64, reg_a), origin, CallFunctionArg(32, RSCRATCH),
+                   inst.hex);
   ABI_PopRegistersAndAdjustStack(caller_save, 0);
 
   FixupBranch branch_out = J(Jump::Near);
diff --git a/Source/Core/Core/PowerPC/Jit64/Jit_FloatingPoint.cpp b/Source/Core/Core/PowerPC/Jit64/Jit_FloatingPoint.cpp
index 75cfbed3d63..bf639fdce27 100644
--- a/Source/Core/Core/PowerPC/Jit64/Jit_FloatingPoint.cpp
+++ b/Source/Core/Core/PowerPC/Jit64/Jit_FloatingPoint.cpp
@@ -475,7 +475,7 @@ void Jit64::fmaddXX(UGeckoInstruction inst)
 
       BitSet32 registers_in_use = CallerSavedRegistersInUse();
       ABI_PushRegistersAndAdjustStack(registers_in_use, 0);
-      ABI_CallFunction(static_cast<double (*)(double, double, double)>(&std::fma));
+      QuickCallFunction(static_cast<double (*)(double, double, double)>(&std::fma));
       ABI_PopRegistersAndAdjustStack(registers_in_use, 0);
     }
 
diff --git a/Source/Core/Core/PowerPC/Jit64/Jit_LoadStore.cpp b/Source/Core/Core/PowerPC/Jit64/Jit_LoadStore.cpp
index ec3be83438c..6e771564377 100644
--- a/Source/Core/Core/PowerPC/Jit64/Jit_LoadStore.cpp
+++ b/Source/Core/Core/PowerPC/Jit64/Jit_LoadStore.cpp
@@ -319,19 +319,13 @@ void Jit64::dcbx(UGeckoInstruction inst)
       SwitchToFarCode();
       SetJumpTarget(branch_in);
 
-      // Assert RSCRATCH2 won't be clobbered before it is moved from.
-      static_assert(RSCRATCH2 != ABI_PARAM1);
-
       ABI_PushRegistersAndAdjustStack(bw_caller_save, 0);
-      MOV(64, R(ABI_PARAM1), R(bw_reg_a));
-      // RSCRATCH2 holds the amount of faked branch watch hits. Move RSCRATCH2 first, because
-      // ABI_PARAM2 clobbers RSCRATCH2 on Windows and ABI_PARAM3 clobbers RSCRATCH2 on Linux!
-      MOV(32, R(ABI_PARAM4), R(RSCRATCH2));
+      const auto function = m_ppc_state.msr.IR ? &Core::BranchWatch::HitVirtualTrue_fk_n :
+                                                 &Core::BranchWatch::HitPhysicalTrue_fk_n;
       const PPCAnalyst::CodeOp& op = js.op[2];
-      MOV(64, R(ABI_PARAM2), Imm64(Core::FakeBranchWatchCollectionKey{op.address, op.branchTo}));
-      MOV(32, R(ABI_PARAM3), Imm32(op.inst.hex));
-      ABI_CallFunction(m_ppc_state.msr.IR ? &Core::BranchWatch::HitVirtualTrue_fk_n :
-                                            &Core::BranchWatch::HitPhysicalTrue_fk_n);
+      ABI_CallFunction(function, CallFunctionArg(64, bw_reg_a),
+                       u64(Core::FakeBranchWatchCollectionKey{op.address, op.branchTo}),
+                       op.inst.hex, CallFunctionArg(32, RSCRATCH2));
       ABI_PopRegistersAndAdjustStack(bw_caller_save, 0);
 
       FixupBranch branch_out = J(Jump::Near);
@@ -398,13 +392,14 @@ void Jit64::dcbx(UGeckoInstruction inst)
   ABI_PushRegistersAndAdjustStack(registersInUse, 0);
   if (make_loop)
   {
-    ABI_CallFunctionPRR(JitInterface::InvalidateICacheLinesFromJIT, &m_system.GetJitInterface(),
-                        effective_address, loop_counter);
+    ABI_CallFunction(JitInterface::InvalidateICacheLinesFromJIT, &m_system.GetJitInterface(),
+                     CallFunctionArg(32, X64Reg(effective_address)),
+                     CallFunctionArg(32, X64Reg(loop_counter)));
   }
   else
   {
-    ABI_CallFunctionPR(JitInterface::InvalidateICacheLineFromJIT, &m_system.GetJitInterface(),
-                       effective_address);
+    ABI_CallFunction(JitInterface::InvalidateICacheLineFromJIT, &m_system.GetJitInterface(),
+                     CallFunctionArg(32, X64Reg(effective_address)));
   }
   ABI_PopRegistersAndAdjustStack(registersInUse, 0);
   asm_routines.ResetStack(*this);
@@ -494,7 +489,7 @@ void Jit64::dcbz(UGeckoInstruction inst)
   FlushPCBeforeSlowAccess();
   BitSet32 registersInUse = CallerSavedRegistersInUse();
   ABI_PushRegistersAndAdjustStack(registersInUse, 0);
-  ABI_CallFunctionPR(PowerPC::ClearDCacheLineFromJit, &m_mmu, RSCRATCH);
+  ABI_CallFunction(PowerPC::ClearDCacheLineFromJit, &m_mmu, CallFunctionArg(32, RSCRATCH));
   ABI_PopRegistersAndAdjustStack(registersInUse, 0);
 
   if (emit_fast_path)
diff --git a/Source/Core/Core/PowerPC/Jit64/Jit_SystemRegisters.cpp b/Source/Core/Core/PowerPC/Jit64/Jit_SystemRegisters.cpp
index 63313583594..e1cd8cc86f8 100644
--- a/Source/Core/Core/PowerPC/Jit64/Jit_SystemRegisters.cpp
+++ b/Source/Core/Core/PowerPC/Jit64/Jit_SystemRegisters.cpp
@@ -287,7 +287,7 @@ void Jit64::mtspr(UGeckoInstruction inst)
     FixupBranch dont_reset_icache = J_CC(CC_NC);
     BitSet32 regs = CallerSavedRegistersInUse();
     ABI_PushRegistersAndAdjustStack(regs, 0);
-    ABI_CallFunctionPP(DoICacheReset, &m_ppc_state, &m_system.GetJitInterface());
+    ABI_CallFunction(DoICacheReset, &m_ppc_state, &m_system.GetJitInterface());
     ABI_PopRegistersAndAdjustStack(regs, 0);
     SetJumpTarget(dont_reset_icache);
     return;
diff --git a/Source/Core/Core/PowerPC/Jit64Common/EmuCodeBlock.cpp b/Source/Core/Core/PowerPC/Jit64Common/EmuCodeBlock.cpp
index 58b34698adf..8d6f7eae374 100644
--- a/Source/Core/Core/PowerPC/Jit64Common/EmuCodeBlock.cpp
+++ b/Source/Core/Core/PowerPC/Jit64Common/EmuCodeBlock.cpp
@@ -280,7 +280,7 @@ private:
   void CallLambda(int sbits, const std::function<T(Core::System&, u32)>* lambda)
   {
     m_code->ABI_PushRegistersAndAdjustStack(m_registers_in_use, 0);
-    m_code->ABI_CallLambdaPC(lambda, m_system, m_address);
+    m_code->ABI_CallLambda(lambda, m_system, m_address);
     m_code->ABI_PopRegistersAndAdjustStack(m_registers_in_use, 0);
     MoveOpArgToReg(sbits, R(ABI_RETURN));
   }
@@ -405,16 +405,16 @@ void EmuCodeBlock::SafeLoadToReg(X64Reg reg_value, const Gen::OpArg& opAddress,
   switch (accessSize)
   {
   case 64:
-    ABI_CallFunctionPR(PowerPC::ReadFromJit<u64>, &m_jit.m_mmu, reg_addr);
+    ABI_CallFunction(PowerPC::ReadFromJit<u64>, &m_jit.m_mmu, CallFunctionArg(32, reg_addr));
     break;
   case 32:
-    ABI_CallFunctionPR(PowerPC::ReadFromJit<u32>, &m_jit.m_mmu, reg_addr);
+    ABI_CallFunction(PowerPC::ReadFromJit<u32>, &m_jit.m_mmu, CallFunctionArg(32, reg_addr));
     break;
   case 16:
-    ABI_CallFunctionPR(PowerPC::ReadFromJit<u16>, &m_jit.m_mmu, reg_addr);
+    ABI_CallFunction(PowerPC::ReadFromJit<u16>, &m_jit.m_mmu, CallFunctionArg(32, reg_addr));
     break;
   case 8:
-    ABI_CallFunctionPR(PowerPC::ReadFromJit<u8>, &m_jit.m_mmu, reg_addr);
+    ABI_CallFunction(PowerPC::ReadFromJit<u8>, &m_jit.m_mmu, CallFunctionArg(32, reg_addr));
     break;
   }
   ABI_PopRegistersAndAdjustStack(registersInUse, rsp_alignment);
@@ -468,16 +468,16 @@ void EmuCodeBlock::SafeLoadToRegImmediate(X64Reg reg_value, u32 address, int acc
   switch (accessSize)
   {
   case 64:
-    ABI_CallFunctionPC(PowerPC::ReadFromJit<u64>, &m_jit.m_mmu, address);
+    ABI_CallFunction(PowerPC::ReadFromJit<u64>, &m_jit.m_mmu, address);
     break;
   case 32:
-    ABI_CallFunctionPC(PowerPC::ReadFromJit<u32>, &m_jit.m_mmu, address);
+    ABI_CallFunction(PowerPC::ReadFromJit<u32>, &m_jit.m_mmu, address);
     break;
   case 16:
-    ABI_CallFunctionPC(PowerPC::ReadFromJit<u16>, &m_jit.m_mmu, address);
+    ABI_CallFunction(PowerPC::ReadFromJit<u16>, &m_jit.m_mmu, address);
     break;
   case 8:
-    ABI_CallFunctionPC(PowerPC::ReadFromJit<u8>, &m_jit.m_mmu, address);
+    ABI_CallFunction(PowerPC::ReadFromJit<u8>, &m_jit.m_mmu, address);
     break;
   }
   ABI_PopRegistersAndAdjustStack(registersInUse, 0);
@@ -573,34 +573,23 @@ void EmuCodeBlock::SafeWriteRegToReg(OpArg reg_value, X64Reg reg_addr, int acces
   size_t rsp_alignment = (flags & SAFE_LOADSTORE_NO_PROLOG) ? 8 : 0;
   ABI_PushRegistersAndAdjustStack(registersInUse, rsp_alignment);
 
-  // If the input is an immediate, we need to put it in a register.
-  X64Reg reg;
-  if (reg_value.IsImm())
-  {
-    reg = reg_addr == ABI_PARAM1 ? RSCRATCH : ABI_PARAM1;
-    MOV(accessSize, R(reg), reg_value);
-  }
-  else
-  {
-    reg = reg_value.GetSimpleReg();
-  }
-
   switch (accessSize)
   {
   case 64:
-    ABI_CallFunctionPRR(swap ? PowerPC::WriteFromJit<u64> : PowerPC::WriteU64SwapFromJit,
-                        &m_jit.m_mmu, reg, reg_addr);
+    ABI_CallFunction(swap ? PowerPC::WriteFromJit<u64> : PowerPC::WriteU64SwapFromJit, &m_jit.m_mmu,
+                     CallFunctionArg(accessSize, reg_value), CallFunctionArg(32, reg_addr));
     break;
   case 32:
-    ABI_CallFunctionPRR(swap ? PowerPC::WriteFromJit<u32> : PowerPC::WriteU32SwapFromJit,
-                        &m_jit.m_mmu, reg, reg_addr);
+    ABI_CallFunction(swap ? PowerPC::WriteFromJit<u32> : PowerPC::WriteU32SwapFromJit, &m_jit.m_mmu,
+                     CallFunctionArg(accessSize, reg_value), CallFunctionArg(32, reg_addr));
     break;
   case 16:
-    ABI_CallFunctionPRR(swap ? PowerPC::WriteFromJit<u16> : PowerPC::WriteU16SwapFromJit,
-                        &m_jit.m_mmu, reg, reg_addr);
+    ABI_CallFunction(swap ? PowerPC::WriteFromJit<u16> : PowerPC::WriteU16SwapFromJit, &m_jit.m_mmu,
+                     CallFunctionArg(accessSize, reg_value), CallFunctionArg(32, reg_addr));
     break;
   case 8:
-    ABI_CallFunctionPRR(PowerPC::WriteFromJit<u8>, &m_jit.m_mmu, reg, reg_addr);
+    ABI_CallFunction(PowerPC::WriteFromJit<u8>, &m_jit.m_mmu,
+                     CallFunctionArg(accessSize, reg_value), CallFunctionArg(32, reg_addr));
     break;
   }
   ABI_PopRegistersAndAdjustStack(registersInUse, rsp_alignment);
@@ -669,16 +658,20 @@ bool EmuCodeBlock::WriteToConstAddress(int accessSize, OpArg arg, u32 address,
     switch (accessSize)
     {
     case 64:
-      ABI_CallFunctionPAC(64, PowerPC::WriteFromJit<u64>, &m_jit.m_mmu, arg, address);
+      ABI_CallFunction(PowerPC::WriteFromJit<u64>, &m_jit.m_mmu, CallFunctionArg(accessSize, arg),
+                       address);
       break;
     case 32:
-      ABI_CallFunctionPAC(32, PowerPC::WriteFromJit<u32>, &m_jit.m_mmu, arg, address);
+      ABI_CallFunction(PowerPC::WriteFromJit<u32>, &m_jit.m_mmu, CallFunctionArg(accessSize, arg),
+                       address);
       break;
     case 16:
-      ABI_CallFunctionPAC(16, PowerPC::WriteFromJit<u16>, &m_jit.m_mmu, arg, address);
+      ABI_CallFunction(PowerPC::WriteFromJit<u16>, &m_jit.m_mmu, CallFunctionArg(accessSize, arg),
+                       address);
       break;
     case 8:
-      ABI_CallFunctionPAC(8, PowerPC::WriteFromJit<u8>, &m_jit.m_mmu, arg, address);
+      ABI_CallFunction(PowerPC::WriteFromJit<u8>, &m_jit.m_mmu, CallFunctionArg(accessSize, arg),
+                       address);
       break;
     }
     ABI_PopRegistersAndAdjustStack(registersInUse, 0);
diff --git a/Source/Core/Core/PowerPC/Jit64Common/Jit64AsmCommon.cpp b/Source/Core/Core/PowerPC/Jit64Common/Jit64AsmCommon.cpp
index a08aaad0f4b..e828b92fc22 100644
--- a/Source/Core/Core/PowerPC/Jit64Common/Jit64AsmCommon.cpp
+++ b/Source/Core/Core/PowerPC/Jit64Common/Jit64AsmCommon.cpp
@@ -207,7 +207,7 @@ void CommonAsmRoutines::GenFrsqrte()
 
   SetJumpTarget(denormal);
   ABI_PushRegistersAndAdjustStack(QUANTIZED_REGS_TO_SAVE, 8);
-  ABI_CallFunction(Common::ApproximateReciprocalSquareRoot);
+  QuickCallFunction(Common::ApproximateReciprocalSquareRoot);
   ABI_PopRegistersAndAdjustStack(QUANTIZED_REGS_TO_SAVE, 8);
   RET();
 
@@ -278,7 +278,7 @@ void CommonAsmRoutines::GenFres()
 
   SetJumpTarget(complex);
   ABI_PushRegistersAndAdjustStack(QUANTIZED_REGS_TO_SAVE, 8);
-  ABI_CallFunction(Common::ApproximateReciprocal);
+  QuickCallFunction(Common::ApproximateReciprocal);
   ABI_PopRegistersAndAdjustStack(QUANTIZED_REGS_TO_SAVE, 8);
   RET();
 
diff --git a/Source/UnitTests/Common/CMakeLists.txt b/Source/UnitTests/Common/CMakeLists.txt
index a2e21d7a802..f407632f376 100644
--- a/Source/UnitTests/Common/CMakeLists.txt
+++ b/Source/UnitTests/Common/CMakeLists.txt
@@ -23,6 +23,7 @@ add_dolphin_test(SwapTest SwapTest.cpp)
 add_dolphin_test(WorkQueueThreadTest WorkQueueThreadTest.cpp)
 
 if (_M_X86_64)
+  add_dolphin_test(x64ABITest x64ABITest.cpp)
   add_dolphin_test(x64EmitterTest x64EmitterTest.cpp)
   target_link_libraries(x64EmitterTest PRIVATE bdisasm)
 elseif (_M_ARM_64)
diff --git a/Source/UnitTests/Common/x64ABITest.cpp b/Source/UnitTests/Common/x64ABITest.cpp
new file mode 100644
index 00000000000..c7cf5776982
--- /dev/null
+++ b/Source/UnitTests/Common/x64ABITest.cpp
@@ -0,0 +1,388 @@
+// Copyright 2025 Dolphin Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <algorithm>
+#include <bit>
+#include <concepts>
+
+#include "Common/x64ABI.h"
+#include "Common/x64Emitter.h"
+
+#include <gtest/gtest.h>
+
+using namespace Gen;
+
+namespace
+{
+u32 ZeroParameterFunction()
+{
+  return 123;
+}
+
+template <std::integral T>
+u32 OneParameterFunction(T a)
+{
+  return a + 23;
+}
+
+u32 TwoParameterFunction(u64 a, u64 b)
+{
+  return a * 10 + b + 3;
+}
+
+u32 ThreeParameterFunction(u64 a, u64 b, u64 c)
+{
+  return a * 10 + b + c / 10;
+}
+
+u32 FourParameterFunction(u64 a, u64 b, u32 c, u32 d)
+{
+  return a == 0x0102030405060708 && b == 0x090a0b0c0d0e0f10 && c == 0x11121314 && d == 0x15161718 ?
+             123 :
+             4;
+}
+
+class TestCallFunction : public X64CodeBlock
+{
+public:
+  TestCallFunction() { AllocCodeSpace(4096); }
+
+  template <typename F>
+  void Emit(F f)
+  {
+    ResetCodePtr();
+
+    m_code_pointer = GetCodePtr();
+    {
+      const Common::ScopedJITPageWriteAndNoExecute enable_jit_page_writes;
+
+      ABI_PushRegistersAndAdjustStack(ABI_ALL_CALLEE_SAVED, 8, 16);
+      f();
+      ABI_PopRegistersAndAdjustStack(ABI_ALL_CALLEE_SAVED, 8, 16);
+      RET();
+    }
+  }
+
+  void Run()
+  {
+    const u64 actual = std::bit_cast<u64 (*)()>(m_code_pointer)();
+    constexpr u64 expected = 123;
+    EXPECT_EQ(expected, actual);
+  }
+
+private:
+  const u8* m_code_pointer = nullptr;
+};
+
+}  // namespace
+
+TEST(x64ABITest, CallFunction_ZeroParameters)
+{
+  TestCallFunction test;
+  test.Emit([&] { test.ABI_CallFunction(&ZeroParameterFunction); });
+  test.Run();
+}
+
+TEST(x64ABITest, CallFunction_OneConstantParameter)
+{
+  TestCallFunction test;
+  test.Emit([&] { test.ABI_CallFunction(&OneParameterFunction<u64>, 100); });
+  test.Run();
+}
+
+TEST(x64ABITest, CallFunction_OneImm64Parameter)
+{
+  TestCallFunction test;
+  test.Emit([&] {
+    test.ABI_CallFunction(&OneParameterFunction<u64>, XEmitter::CallFunctionArg(64, Imm64(100)));
+  });
+  test.Run();
+}
+
+TEST(x64ABITest, CallFunction_OneImm32Parameter)
+{
+  TestCallFunction test;
+  test.Emit([&] {
+    test.ABI_CallFunction(&OneParameterFunction<u32>, XEmitter::CallFunctionArg(32, Imm32(100)));
+  });
+  test.Run();
+}
+
+TEST(x64ABITest, CallFunction_OneImm16Parameter)
+{
+  TestCallFunction test;
+  test.Emit([&] {
+    test.ABI_CallFunction(&OneParameterFunction<u16>, XEmitter::CallFunctionArg(16, Imm16(100)));
+  });
+  test.Run();
+}
+
+TEST(x64ABITest, CallFunction_OneImm8Parameter)
+{
+  TestCallFunction test;
+  test.Emit([&] {
+    test.ABI_CallFunction(&OneParameterFunction<u8>, XEmitter::CallFunctionArg(8, Imm8(100)));
+  });
+  test.Run();
+}
+
+TEST(x64ABITest, CallFunction_One64BitRegisterParameterNoMov)
+{
+  TestCallFunction test;
+  test.Emit([&] {
+    test.MOV(64, R(ABI_PARAM1), Imm64(100));
+    test.ABI_CallFunction(&OneParameterFunction<u64>, XEmitter::CallFunctionArg(64, ABI_PARAM1));
+  });
+  test.Run();
+}
+
+TEST(x64ABITest, CallFunction_One64BitRegisterParameterMov)
+{
+  TestCallFunction test;
+  test.Emit([&] {
+    test.MOV(64, R(ABI_PARAM2), Imm64(100));
+    test.ABI_CallFunction(&OneParameterFunction<u64>, XEmitter::CallFunctionArg(64, ABI_PARAM2));
+  });
+  test.Run();
+}
+
+TEST(x64ABITest, CallFunction_One32BitRegisterParameterNoMov)
+{
+  TestCallFunction test;
+  test.Emit([&] {
+    test.MOV(64, R(ABI_PARAM1), Imm64(0x0101010100000064));
+    test.ABI_CallFunction(&OneParameterFunction<u32>, XEmitter::CallFunctionArg(32, ABI_PARAM1));
+  });
+  test.Run();
+}
+
+TEST(x64ABITest, CallFunction_One32BitRegisterParameterMov)
+{
+  TestCallFunction test;
+  test.Emit([&] {
+    test.MOV(64, R(ABI_PARAM2), Imm64(0x0101010100000064));
+    test.ABI_CallFunction(&OneParameterFunction<u32>, XEmitter::CallFunctionArg(32, ABI_PARAM2));
+  });
+  test.Run();
+}
+
+TEST(x64ABITest, CallFunction_One16BitRegisterParameterNoMov)
+{
+  TestCallFunction test;
+  test.Emit([&] {
+    test.MOV(64, R(ABI_PARAM1), Imm64(0x0101010101010064));
+    test.ABI_CallFunction(&OneParameterFunction<u16>, XEmitter::CallFunctionArg(16, ABI_PARAM1));
+  });
+  test.Run();
+}
+
+TEST(x64ABITest, CallFunction_One16BitRegisterParameterMov)
+{
+  TestCallFunction test;
+  test.Emit([&] {
+    test.MOV(64, R(ABI_PARAM2), Imm64(0x0101010101010064));
+    test.ABI_CallFunction(&OneParameterFunction<u16>, XEmitter::CallFunctionArg(16, ABI_PARAM2));
+  });
+  test.Run();
+}
+
+TEST(x64ABITest, CallFunction_One8BitRegisterParameterNoMov)
+{
+  TestCallFunction test;
+  test.Emit([&] {
+    test.MOV(64, R(ABI_PARAM1), Imm64(0x0101010101010164));
+    test.ABI_CallFunction(&OneParameterFunction<u8>, XEmitter::CallFunctionArg(8, ABI_PARAM1));
+  });
+  test.Run();
+}
+
+TEST(x64ABITest, CallFunction_One8BitRegisterParameterMov)
+{
+  TestCallFunction test;
+  test.Emit([&] {
+    test.MOV(64, R(ABI_PARAM2), Imm64(0x0101010101010164));
+    test.ABI_CallFunction(&OneParameterFunction<u8>, XEmitter::CallFunctionArg(8, ABI_PARAM2));
+  });
+  test.Run();
+}
+
+TEST(x64ABITest, CallFunction_One64BitMemoryParameter)
+{
+  constexpr u64 value = 100;
+  TestCallFunction test;
+  test.Emit([&] {
+    test.MOV(64, R(RAX), ImmPtr(&value));
+    test.ABI_CallFunction(&OneParameterFunction<u64>, XEmitter::CallFunctionArg(64, MatR(RAX)));
+  });
+  test.Run();
+}
+
+TEST(x64ABITest, CallFunction_One32BitMemoryParameter)
+{
+  constexpr u32 value = 100;
+  TestCallFunction test;
+  test.Emit([&] {
+    test.MOV(64, R(ABI_PARAM3), ImmPtr(&value));
+    test.ABI_CallFunction(&OneParameterFunction<u32>,
+                          XEmitter::CallFunctionArg(32, MatR(ABI_PARAM3)));
+  });
+  test.Run();
+}
+
+TEST(x64ABITest, CallFunction_One16BitMemoryParameter)
+{
+  constexpr u16 value = 100;
+  TestCallFunction test;
+  test.Emit([&] {
+    test.MOV(64, R(ABI_PARAM2), ImmPtr(&value));
+    test.ABI_CallFunction(&OneParameterFunction<u16>,
+                          XEmitter::CallFunctionArg(16, MatR(ABI_PARAM2)));
+  });
+  test.Run();
+}
+
+TEST(x64ABITest, CallFunction_One8BitMemoryParameter)
+{
+  constexpr u8 value = 100;
+  TestCallFunction test;
+  test.Emit([&] {
+    test.MOV(64, R(ABI_PARAM1), ImmPtr(&value));
+    test.ABI_CallFunction(&OneParameterFunction<u8>,
+                          XEmitter::CallFunctionArg(8, MatR(ABI_PARAM1)));
+  });
+  test.Run();
+}
+
+TEST(x64ABITest, CallFunction_TwoRegistersMixed)
+{
+  TestCallFunction test;
+  test.Emit([&] {
+    test.MOV(32, R(ABI_PARAM1), Imm32(20));
+    test.ABI_CallFunction(&TwoParameterFunction, 10, XEmitter::CallFunctionArg(32, ABI_PARAM1));
+  });
+  test.Run();
+}
+
+TEST(x64ABITest, CallFunction_TwoRegistersCycle)
+{
+  TestCallFunction test;
+  test.Emit([&] {
+    test.MOV(32, R(ABI_PARAM1), Imm32(20));
+    test.MOV(32, R(ABI_PARAM2), Imm32(10));
+    test.ABI_CallFunction(&TwoParameterFunction, XEmitter::CallFunctionArg(32, ABI_PARAM2),
+                          XEmitter::CallFunctionArg(32, ABI_PARAM1));
+  });
+  test.Run();
+}
+
+TEST(x64ABITest, CallFunction_ThreeRegistersMixed)
+{
+  TestCallFunction test;
+  test.Emit([&] {
+    test.MOV(32, R(ABI_PARAM2), Imm32(10));
+    test.MOV(32, R(ABI_PARAM3), Imm32(20));
+    test.ABI_CallFunction(&ThreeParameterFunction, XEmitter::CallFunctionArg(32, ABI_PARAM2),
+                          XEmitter::CallFunctionArg(32, ABI_PARAM3), 30);
+  });
+  test.Run();
+}
+
+TEST(x64ABITest, CallFunction_ThreeRegistersCycle1)
+{
+  TestCallFunction test;
+  test.Emit([&] {
+    test.MOV(32, R(ABI_PARAM1), Imm32(30));
+    test.MOV(32, R(ABI_PARAM2), Imm32(10));
+    test.MOV(32, R(ABI_PARAM3), Imm32(20));
+    test.ABI_CallFunction(&ThreeParameterFunction, XEmitter::CallFunctionArg(32, ABI_PARAM2),
+                          XEmitter::CallFunctionArg(32, ABI_PARAM3),
+                          XEmitter::CallFunctionArg(32, ABI_PARAM1));
+  });
+  test.Run();
+}
+
+TEST(x64ABITest, CallFunction_ThreeRegistersCycle2)
+{
+  TestCallFunction test;
+  test.Emit([&] {
+    test.MOV(32, R(ABI_PARAM1), Imm32(20));
+    test.MOV(32, R(ABI_PARAM2), Imm32(30));
+    test.MOV(32, R(ABI_PARAM3), Imm32(10));
+    test.ABI_CallFunction(&ThreeParameterFunction, XEmitter::CallFunctionArg(32, ABI_PARAM3),
+                          XEmitter::CallFunctionArg(32, ABI_PARAM1),
+                          XEmitter::CallFunctionArg(32, ABI_PARAM2));
+  });
+  test.Run();
+}
+
+TEST(x64ABITest, CallFunction_ThreeMemoryRegistersCycle1)
+{
+  constexpr u32 value1 = 10;
+  constexpr u32 value2 = 20;
+  constexpr u32 value3 = 30;
+  TestCallFunction test;
+  test.Emit([&] {
+    test.MOV(64, R(ABI_PARAM1), ImmPtr(&value3));
+    test.MOV(64, R(ABI_PARAM2), ImmPtr(&value1));
+    test.MOV(64, R(ABI_PARAM3), ImmPtr(&value2));
+    test.ABI_CallFunction(&ThreeParameterFunction, XEmitter::CallFunctionArg(32, MatR(ABI_PARAM2)),
+                          XEmitter::CallFunctionArg(32, MatR(ABI_PARAM3)),
+                          XEmitter::CallFunctionArg(32, MatR(ABI_PARAM1)));
+  });
+  test.Run();
+}
+
+TEST(x64ABITest, CallFunction_ThreeMemoryRegistersCycle2)
+{
+  constexpr u32 value1 = 10;
+  constexpr u32 value2 = 20;
+  constexpr u32 value3 = 30;
+  TestCallFunction test;
+  test.Emit([&] {
+    test.MOV(64, R(ABI_PARAM1), ImmPtr(&value2));
+    test.MOV(64, R(ABI_PARAM2), ImmPtr(&value3));
+    test.MOV(64, R(ABI_PARAM3), ImmPtr(&value1));
+    test.ABI_CallFunction(&ThreeParameterFunction, XEmitter::CallFunctionArg(32, MatR(ABI_PARAM3)),
+                          XEmitter::CallFunctionArg(32, MatR(ABI_PARAM1)),
+                          XEmitter::CallFunctionArg(32, MatR(ABI_PARAM2)));
+  });
+  test.Run();
+}
+
+TEST(x64ABITest, CallFunction_FourRegistersMixed)
+{
+  // Loosely based on an actual piece of code where we call Core::BranchWatch::HitVirtualTrue_fk_n
+  TestCallFunction test;
+  test.Emit([&] {
+    test.MOV(64, R(RAX), Imm64(0x0102030405060708));
+    test.MOV(32, R(RDX), Imm32(0x15161718));
+    test.ABI_CallFunction(&FourParameterFunction, XEmitter::CallFunctionArg(64, RAX),
+                          0x090a0b0c0d0e0f10, 0x11121314, XEmitter::CallFunctionArg(32, RDX));
+  });
+  test.Run();
+}
+
+TEST(x64ABITest, CallFunction_FourRegistersComplexAddressing)
+{
+  constexpr u64 value1 = 0x0102030405060708;
+  constexpr u64 value2 = 0x090a0b0c0d0e0f10;
+  constexpr u32 value3 = 0x11121314;
+  constexpr u32 value4 = 0x15161718;
+  TestCallFunction test;
+  test.Emit([&] {
+    test.MOV(64, R(ABI_PARAM1), Imm32(3));
+    test.MOV(64, R(ABI_PARAM2), Imm64(reinterpret_cast<uintptr_t>(&value1) - 3));
+    test.MOV(64, R(ABI_PARAM4), Imm64(reinterpret_cast<uintptr_t>(&value2) / 4 + 3));
+    test.MOV(64, R(ABI_PARAM3), Imm64(reinterpret_cast<uintptr_t>(&value3) - 30));
+    test.MOV(64, R(RAX), Imm32(15));
+    static_assert(std::count(ABI_PARAMS.begin(), ABI_PARAMS.end(), RAX) == 0);
+    test.ABI_CallFunction(
+        &FourParameterFunction, XEmitter::CallFunctionArg(64, MRegSum(ABI_PARAM1, ABI_PARAM2)),
+        XEmitter::CallFunctionArg(64, MScaled(ABI_PARAM4, SCALE_4, -12)),
+        XEmitter::CallFunctionArg(32, MComplex(ABI_PARAM3, ABI_PARAM1, SCALE_8, 6)),
+        XEmitter::CallFunctionArg(32, MComplex(ABI_PARAM3, RAX, SCALE_2,
+                                               reinterpret_cast<uintptr_t>(&value4) -
+                                                   reinterpret_cast<uintptr_t>(&value3))));
+  });
+  test.Run();
+}
diff --git a/Source/UnitTests/Core/PowerPC/Jit64Common/ConvertDoubleToSingle.cpp b/Source/UnitTests/Core/PowerPC/Jit64Common/ConvertDoubleToSingle.cpp
index 05c80854b2f..d3eec35b6cc 100644
--- a/Source/UnitTests/Core/PowerPC/Jit64Common/ConvertDoubleToSingle.cpp
+++ b/Source/UnitTests/Core/PowerPC/Jit64Common/ConvertDoubleToSingle.cpp
@@ -40,7 +40,7 @@ public:
 
     // Call
     MOVQ_xmm(XMM0, R(ABI_PARAM1));
-    ABI_CallFunction(raw_cdts);
+    QuickCallFunction(raw_cdts);
     MOV(32, R(ABI_RETURN), R(RSCRATCH));
 
     ABI_PopRegistersAndAdjustStack(ABI_ALL_CALLEE_SAVED, 8, 16);
diff --git a/Source/UnitTests/Core/PowerPC/Jit64Common/Frsqrte.cpp b/Source/UnitTests/Core/PowerPC/Jit64Common/Frsqrte.cpp
index a59f577c7b5..f704ad2bf58 100644
--- a/Source/UnitTests/Core/PowerPC/Jit64Common/Frsqrte.cpp
+++ b/Source/UnitTests/Core/PowerPC/Jit64Common/Frsqrte.cpp
@@ -47,7 +47,7 @@ public:
 
     // Call
     MOVQ_xmm(XMM0, R(ABI_PARAM1));
-    ABI_CallFunction(raw_frsqrte);
+    QuickCallFunction(raw_frsqrte);
     MOVQ_xmm(R(ABI_RETURN), XMM0);
 
     ABI_PopRegistersAndAdjustStack(ABI_ALL_CALLEE_SAVED, 8, 16);
diff --git a/Source/UnitTests/UnitTests.vcxproj b/Source/UnitTests/UnitTests.vcxproj
index 698e33bc37a..ebeb58a3433 100644
--- a/Source/UnitTests/UnitTests.vcxproj
+++ b/Source/UnitTests/UnitTests.vcxproj
@@ -79,6 +79,7 @@
   </ItemGroup>
   <!--Arch-specific tests-->
   <ItemGroup Condition="'$(Platform)'=='x64'">
+    <ClCompile Include="Common\x64ABITest.cpp" />
     <ClCompile Include="Common\x64EmitterTest.cpp" />
     <ClCompile Include="Core\PowerPC\Jit64Common\ConvertDoubleToSingle.cpp" />
     <ClCompile Include="Core\PowerPC\Jit64Common\Frsqrte.cpp" />