diff --git a/CMakeLists.txt b/CMakeLists.txt
index febba44798..aefb427121 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -37,6 +37,7 @@ option(USE_PDB_DEBUGINFO "Builds debug info in PDB format" FALSE)
 
 set (X86_32_TOOLCHAIN_FILE "${CMAKE_CURRENT_SOURCE_DIR}/toolchain_x86_32.cmake" CACHE FILEPATH "Toolchain file for the (cross-)compiler targeting i686")
 set (X86_64_TOOLCHAIN_FILE "${CMAKE_CURRENT_SOURCE_DIR}/toolchain_x86_64.cmake" CACHE FILEPATH "Toolchain file for the (cross-)compiler targeting x86_64")
+set (X86_DEV_ROOTFS "/" CACHE FILEPATH "Toolchain file for the (cross-)compiler targeting x86_64")
 set (DATA_DIRECTORY "${CMAKE_INSTALL_PREFIX}/share/fex-emu" CACHE PATH "global data directory")
 
 string(FIND ${CMAKE_BASE_NAME} mingw CONTAINS_MINGW)
@@ -479,6 +480,7 @@ if (BUILD_THUNKS)
       "-DCMAKE_INSTALL_PREFIX=${CMAKE_INSTALL_PREFIX}"
       "-DFEX_PROJECT_SOURCE_DIR=${FEX_PROJECT_SOURCE_DIR}"
       "-DGENERATOR_EXE=$<TARGET_FILE:thunkgen>"
+      "-DX86_DEV_ROOTFS=${X86_DEV_ROOTFS}"
     INSTALL_COMMAND ""
     BUILD_ALWAYS ON
     DEPENDS thunkgen
@@ -497,6 +499,7 @@ if (BUILD_THUNKS)
       "-DCMAKE_INSTALL_PREFIX=${CMAKE_INSTALL_PREFIX}"
       "-DFEX_PROJECT_SOURCE_DIR=${FEX_PROJECT_SOURCE_DIR}"
       "-DGENERATOR_EXE=$<TARGET_FILE:thunkgen>"
+      "-DX86_DEV_ROOTFS=${X86_DEV_ROOTFS}"
     INSTALL_COMMAND ""
     BUILD_ALWAYS ON
     DEPENDS thunkgen
diff --git a/ThunkLibs/Generator/main.cpp b/ThunkLibs/Generator/main.cpp
index a378cc0902..4a504405ad 100644
--- a/ThunkLibs/Generator/main.cpp
+++ b/ThunkLibs/Generator/main.cpp
@@ -4,6 +4,7 @@
 #include "llvm/Support/Signals.h"
 
 #include <iostream>
+#include <optional>
 #include <string>
 
 #include "interface.h"
@@ -17,7 +18,7 @@ void print_usage(const char* program_name) {
 int main(int argc, char* const argv[]) {
   llvm::sys::PrintStackTraceOnErrorSignal(argv[0]);
 
-  if (argc < 5) {
+  if (argc < 6) {
     print_usage(argv[0]);
     return EXIT_FAILURE;
   }
@@ -32,7 +33,7 @@ int main(int argc, char* const argv[]) {
   }
 
   // Process arguments before the "--" separator
-  if (argc != 5 && argc != 6) {
+  if (argc != 6 && argc != 7) {
     print_usage(argv[0]);
     return EXIT_FAILURE;
   }
@@ -42,6 +43,7 @@ int main(int argc, char* const argv[]) {
   const std::string libname = *arg++;
   const std::string target_abi = *arg++;
   const std::string output_filename = *arg++;
+  const std::string x86_rootfs = *arg++;
 
   OutputFilenames output_filenames;
   if (target_abi == "-host") {
@@ -65,27 +67,52 @@ int main(int argc, char* const argv[]) {
 
   ClangTool GuestTool = Tool;
 
-  {
-    const bool is_32bit_guest = (argv[5] == std::string_view {"-for-32bit-guest"});
-    auto append_guest_args = [is_32bit_guest](const clang::tooling::CommandLineArguments& Args, clang::StringRef) {
-      clang::tooling::CommandLineArguments AdjustedArgs = Args;
-      const char* platform = is_32bit_guest ? "i686" : "x86_64";
-      if (is_32bit_guest) {
-        AdjustedArgs.push_back("-m32");
-        AdjustedArgs.push_back("-DIS_32BIT_THUNK");
-      }
-      AdjustedArgs.push_back(std::string {"--target="} + platform + "-linux-unknown");
-      AdjustedArgs.push_back("-isystem");
-      AdjustedArgs.push_back(std::string {"/usr/"} + platform + "-linux-gnu/include/");
-      AdjustedArgs.push_back("-DGUEST_THUNK_LIBRARY");
-      return AdjustedArgs;
-    };
-    GuestTool.appendArgumentsAdjuster(append_guest_args);
-  }
-
+  auto append_x86_rootfs_includes = [&x86_rootfs](clang::tooling::CommandLineArguments& Args, const char* triple) {
+    if (x86_rootfs == "/") {
+      return;
+    }
+
+    Args.push_back("--sysroot");
+    Args.push_back(x86_rootfs);
+
+    // The dev rootfs is only really needed for the standard library.
+    // Other libraries generally don't have platform specific headers.
+    Args.push_back("-idirafter");
+    Args.push_back("/usr/include/");
+  };
+
+  // Analyse data layout for guest ABI
+  const bool is_32bit_guest = (argv[6] == std::string_view {"-for-32bit-guest"});
+  GuestTool.appendArgumentsAdjuster([&](const clang::tooling::CommandLineArguments& Args, clang::StringRef) {
+    clang::tooling::CommandLineArguments AdjustedArgs = Args;
+    const char* platform = is_32bit_guest ? "i686-linux-gnu" : "x86_64-linux-gnu";
+    if (is_32bit_guest) {
+      AdjustedArgs.push_back("-m32");
+      AdjustedArgs.push_back("-DIS_32BIT_THUNK");
+    }
+    AdjustedArgs.push_back("-DGUEST_THUNK_LIBRARY");
+    AdjustedArgs.push_back(std::string {"--target="} + platform);
+    AdjustedArgs.push_back("-isystem");
+    AdjustedArgs.push_back(std::string {"/usr/"} + platform + "/include/");
+
+    append_x86_rootfs_includes(AdjustedArgs, platform);
+
+    return AdjustedArgs;
+  });
   auto data_layout_analysis_factory = std::make_unique<AnalyzeDataLayoutActionFactory>();
   GuestTool.run(data_layout_analysis_factory.get());
   auto& data_layout = data_layout_analysis_factory->GetDataLayout();
 
+  // Run generator for target ABI
+  Tool.appendArgumentsAdjuster([&](const clang::tooling::CommandLineArguments& Args, clang::StringRef) {
+    clang::tooling::CommandLineArguments AdjustedArgs = Args;
+    AdjustedArgs.push_back("-DIS_HOST_THUNKGEN_PASS");
+    if (target_abi == "-guest") {
+      const char* platform = is_32bit_guest ? "i686-linux-gnu" : "x86_64-linux-gnu";
+      append_x86_rootfs_includes(AdjustedArgs, platform);
+    }
+
+    return AdjustedArgs;
+  });
   return Tool.run(std::make_unique<GenerateThunkLibsActionFactory>(std::move(libname), std::move(output_filenames), data_layout).get());
 }
diff --git a/ThunkLibs/GuestLibs/CMakeLists.txt b/ThunkLibs/GuestLibs/CMakeLists.txt
index cff9943e9a..4482588597 100644
--- a/ThunkLibs/GuestLibs/CMakeLists.txt
+++ b/ThunkLibs/GuestLibs/CMakeLists.txt
@@ -9,6 +9,10 @@ if (ENABLE_CLANG_THUNKS)
   add_link_options(${LD_OVERRIDE})
 endif()
 
+if (NOT X86_DEV_ROOTFS)
+  message(FATAL_ERROR "X86_DEV_ROOTFS must be set (use \"/\" to ignore)")
+endif()
+
 find_program(CCACHE_PROGRAM ccache)
 if(CCACHE_PROGRAM)
   message(STATUS "CCache enabled for guest thunks")
@@ -77,7 +81,7 @@ function(generate NAME SOURCE_FILE)
     OUTPUT "${OUTFILE}"
     DEPENDS "${GENERATOR_EXE}"
     DEPENDS "${SOURCE_FILE}"
-    COMMAND "${GENERATOR_EXE}" "${SOURCE_FILE}" "${NAME}" "-guest" "${OUTFILE}" ${BITNESS_FLAGS} -- -std=c++20 ${BITNESS_FLAGS2}
+    COMMAND "${GENERATOR_EXE}" "${SOURCE_FILE}" "${NAME}" "-guest" "${OUTFILE}" "${X86_DEV_ROOTFS}" ${BITNESS_FLAGS} -- -std=c++20 ${BITNESS_FLAGS2}
       # Expand compile definitions to space-separated list of -D parameters
       "$<$<BOOL:${compile_prop}>:;-D$<JOIN:${compile_prop},;-D>>"
       # Expand include directories to space-separated list of -isystem parameters
diff --git a/ThunkLibs/HostLibs/CMakeLists.txt b/ThunkLibs/HostLibs/CMakeLists.txt
index 8d8d6b2b24..cec5b81001 100644
--- a/ThunkLibs/HostLibs/CMakeLists.txt
+++ b/ThunkLibs/HostLibs/CMakeLists.txt
@@ -53,7 +53,7 @@ function(generate NAME SOURCE_FILE GUEST_BITNESS)
     OUTPUT "${OUTFILE}"
     DEPENDS "${SOURCE_FILE}"
     DEPENDS thunkgen
-    COMMAND thunkgen "${SOURCE_FILE}" "${NAME}" "-host" "${OUTFILE}" ${BITNESS_FLAGS} -- -std=c++20
+    COMMAND thunkgen "${SOURCE_FILE}" "${NAME}" "-host" "${OUTFILE}" "${X86_DEV_ROOTFS}" ${BITNESS_FLAGS} -- -std=c++20
       # Expand compile definitions to space-separated list of -D parameters
       "$<$<BOOL:${compile_prop}>:;-D$<JOIN:${compile_prop},;-D>>"
       # Expand include directories to space-separated list of -isystem parameters