diff --git a/CMakeLists.txt b/CMakeLists.txt
index f45af84..628225b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -103,6 +103,7 @@
 option(LIBUNWIND_ENABLE_PEDANTIC "Compile with pedantic enabled." ON)
 option(LIBUNWIND_ENABLE_WERROR "Fail and stop if a warning is triggered." OFF)
 option(LIBUNWIND_ENABLE_SHARED "Build libunwind as a shared library." ON)
+option(LIBUNWIND_ENABLE_CROSS_UNWINDING "Enable cross-platform unwinding support." ON)
 
 set(LIBUNWIND_GCC_TOOLCHAIN "" CACHE STRING "GCC toolchain for cross compiling.")
 set(LIBUNWIND_SYSROOT "" CACHE STRING "Sysroot for cross compiling.")
@@ -202,6 +203,11 @@
   endif ()
 endif ()
 
+# Cross-unwinding
+if (NOT LIBUNWIND_ENABLE_CROSS_UNWINDING)
+  list(APPEND LIBUNWIND_COMPILE_FLAGS -D_LIBUNWIND_IS_NATIVE_ONLY)
+endif ()
+
 # This is the _ONLY_ place where add_definitions is called.
 if (MSVC)
   add_definitions(-D_CRT_SECURE_NO_WARNINGS)
diff --git a/include/__libunwind_config.h b/include/__libunwind_config.h
index 63393d3..099d133 100644
--- a/include/__libunwind_config.h
+++ b/include/__libunwind_config.h
@@ -17,4 +17,43 @@
 #define _LIBUNWIND_ARM_EHABI 0
 #endif
 
+#if defined(_LIBUNWIND_IS_NATIVE_ONLY)
+# if defined(__i386__)
+#  define _LIBUNWIND_TARGET_I386 1
+#  define _LIBUNWIND_CONTEXT_SIZE 8
+#  define _LIBUNWIND_CURSOR_SIZE 19
+# elif defined(__x86_64__)
+#  define _LIBUNWIND_TARGET_X86_64 1
+#  define _LIBUNWIND_CONTEXT_SIZE 21
+#  define _LIBUNWIND_CURSOR_SIZE 33
+# elif defined(__ppc__)
+#  define _LIBUNWIND_TARGET_PPC 1
+#  define _LIBUNWIND_CONTEXT_SIZE 117
+#  define _LIBUNWIND_CURSOR_SIZE 128
+# elif defined(__aarch64__)
+#  define _LIBUNWIND_TARGET_AARCH64 1
+#  define _LIBUNWIND_CONTEXT_SIZE 66
+#  define _LIBUNWIND_CURSOR_SIZE 78
+# elif defined(__arm__)
+#  define _LIBUNWIND_TARGET_ARM 1
+#  define _LIBUNWIND_CONTEXT_SIZE 60
+#  define _LIBUNWIND_CURSOR_SIZE 67
+# elif defined(__or1k__)
+#  define _LIBUNWIND_TARGET_OR1K 1
+#  define _LIBUNWIND_CONTEXT_SIZE 16
+#  define _LIBUNWIND_CURSOR_SIZE 28
+# else
+#  error "Unsupported architecture."
+# endif
+#else // !_LIBUNWIND_IS_NATIVE_ONLY
+# define _LIBUNWIND_TARGET_I386 1
+# define _LIBUNWIND_TARGET_X86_64 1
+# define _LIBUNWIND_TARGET_PPC 1
+# define _LIBUNWIND_TARGET_AARCH64 1
+# define _LIBUNWIND_TARGET_ARM 1
+# define _LIBUNWIND_TARGET_OR1K 1
+# define _LIBUNWIND_CONTEXT_SIZE 128
+# define _LIBUNWIND_CURSOR_SIZE 140
+#endif // _LIBUNWIND_IS_NATIVE_ONLY
+
 #endif // ____LIBUNWIND_CONFIG_H__
diff --git a/include/libunwind.h b/include/libunwind.h
index 6045bec..c5b9633 100644
--- a/include/libunwind.h
+++ b/include/libunwind.h
@@ -46,12 +46,12 @@
 };
 
 struct unw_context_t {
-  uint64_t data[128];
+  uint64_t data[_LIBUNWIND_CONTEXT_SIZE];
 };
 typedef struct unw_context_t unw_context_t;
 
 struct unw_cursor_t {
-  uint64_t data[140];
+  uint64_t data[_LIBUNWIND_CURSOR_SIZE];
 };
 typedef struct unw_cursor_t unw_cursor_t;
 
diff --git a/src/CompactUnwinder.hpp b/src/CompactUnwinder.hpp
index cd9ce3e..f528fba 100644
--- a/src/CompactUnwinder.hpp
+++ b/src/CompactUnwinder.hpp
@@ -27,6 +27,7 @@
 
 namespace libunwind {
 
+#if defined(_LIBUNWIND_TARGET_I386)
 /// CompactUnwinder_x86 uses a compact unwind info to virtually "step" (aka
 /// unwind) by modifying a Registers_x86 register set
 template <typename A>
@@ -255,8 +256,10 @@
   // old esp is before return address
   registers.setSP((uint32_t)returnAddressLocation + 4);
 }
+#endif // _LIBUNWIND_TARGET_I386
 
 
+#if defined(_LIBUNWIND_TARGET_X86_64)
 /// CompactUnwinder_x86_64 uses a compact unwind info to virtually "step" (aka
 /// unwind) by modifying a Registers_x86_64 register set
 template <typename A>
@@ -484,9 +487,11 @@
   // old esp is before return address
   registers.setSP(returnAddressLocation + 8);
 }
+#endif // _LIBUNWIND_TARGET_X86_64
 
 
 
+#if defined(_LIBUNWIND_TARGET_AARCH64)
 /// CompactUnwinder_arm64 uses a compact unwind info to virtually "step" (aka
 /// unwind) by modifying a Registers_arm64 register set
 template <typename A>
@@ -686,6 +691,7 @@
 
   return UNW_STEP_SUCCESS;
 }
+#endif // _LIBUNWIND_TARGET_AARCH64
 
 
 } // namespace libunwind
diff --git a/src/Registers.hpp b/src/Registers.hpp
index 875ea20..51759bd 100644
--- a/src/Registers.hpp
+++ b/src/Registers.hpp
@@ -25,6 +25,7 @@
 struct v128 { uint32_t vec[4]; };
 
 
+#if defined(_LIBUNWIND_TARGET_I386)
 /// Registers_x86 holds the register state of a thread in a 32-bit intel
 /// process.
 class _LIBUNWIND_HIDDEN Registers_x86 {
@@ -86,8 +87,8 @@
 };
 
 inline Registers_x86::Registers_x86(const void *registers) {
-  static_assert(sizeof(Registers_x86) < sizeof(unw_context_t),
-                    "x86 registers do not fit into unw_context_t");
+  static_assert(check_fit<Registers_x86, unw_context_t>::does_fit,
+                "x86 registers do not fit into unw_context_t");
   memcpy(&_registers, registers, sizeof(_registers));
 }
 
@@ -211,8 +212,10 @@
 inline void Registers_x86::setVectorRegister(int, v128) {
   _LIBUNWIND_ABORT("no x86 vector registers");
 }
+#endif // _LIBUNWIND_TARGET_I386
 
 
+#if defined(_LIBUNWIND_TARGET_X86_64)
 /// Registers_x86_64  holds the register state of a thread in a 64-bit intel
 /// process.
 class _LIBUNWIND_HIDDEN Registers_x86_64 {
@@ -278,8 +281,8 @@
 };
 
 inline Registers_x86_64::Registers_x86_64(const void *registers) {
-  static_assert(sizeof(Registers_x86_64) < sizeof(unw_context_t),
-                    "x86_64 registers do not fit into unw_context_t");
+  static_assert(check_fit<Registers_x86_64, unw_context_t>::does_fit,
+                "x86_64 registers do not fit into unw_context_t");
   memcpy(&_registers, registers, sizeof(_registers));
 }
 
@@ -459,8 +462,10 @@
 inline void Registers_x86_64::setVectorRegister(int, v128) {
   _LIBUNWIND_ABORT("no x86_64 vector registers");
 }
+#endif // _LIBUNWIND_TARGET_X86_64
 
 
+#if defined(_LIBUNWIND_TARGET_PPC)
 /// Registers_ppc holds the register state of a thread in a 32-bit PowerPC
 /// process.
 class _LIBUNWIND_HIDDEN Registers_ppc {
@@ -543,8 +548,8 @@
 };
 
 inline Registers_ppc::Registers_ppc(const void *registers) {
-  static_assert(sizeof(Registers_ppc) < sizeof(unw_context_t),
-                    "ppc registers do not fit into unw_context_t");
+  static_assert(check_fit<Registers_ppc, unw_context_t>::does_fit,
+                "ppc registers do not fit into unw_context_t");
   memcpy(&_registers, static_cast<const uint8_t *>(registers),
          sizeof(_registers));
   static_assert(sizeof(ppc_thread_state_t) == 160,
@@ -1023,8 +1028,10 @@
   }
 
 }
+#endif // _LIBUNWIND_TARGET_PPC
 
 
+#if defined(_LIBUNWIND_TARGET_AARCH64)
 /// Registers_arm64  holds the register state of a thread in a 64-bit arm
 /// process.
 class _LIBUNWIND_HIDDEN Registers_arm64 {
@@ -1071,8 +1078,8 @@
 };
 
 inline Registers_arm64::Registers_arm64(const void *registers) {
-  static_assert(sizeof(Registers_arm64) < sizeof(unw_context_t),
-                    "arm64 registers do not fit into unw_context_t");
+  static_assert(check_fit<Registers_arm64, unw_context_t>::does_fit,
+                "arm64 registers do not fit into unw_context_t");
   memcpy(&_registers, registers, sizeof(_registers));
   static_assert(sizeof(GPRs) == 0x110,
                 "expected VFP registers to be at offset 272");
@@ -1289,7 +1296,9 @@
 inline void Registers_arm64::setVectorRegister(int, v128) {
   _LIBUNWIND_ABORT("no arm64 vector register support yet");
 }
+#endif // _LIBUNWIND_TARGET_AARCH64
 
+#if defined(_LIBUNWIND_TARGET_ARM)
 /// Registers_arm holds the register state of a thread in a 32-bit arm
 /// process.
 ///
@@ -1395,8 +1404,8 @@
     _saved_vfp_d16_d31(false),
     _saved_iwmmx(false),
     _saved_iwmmx_control(false) {
-  static_assert(sizeof(Registers_arm) < sizeof(unw_context_t),
-                    "arm registers do not fit into unw_context_t");
+  static_assert(check_fit<Registers_arm, unw_context_t>::does_fit,
+                "arm registers do not fit into unw_context_t");
   // See unw_getcontext() note about data.
   memcpy(&_registers, registers, sizeof(_registers));
   memset(&_vfp_d0_d15_pad, 0, sizeof(_vfp_d0_d15_pad));
@@ -1711,6 +1720,10 @@
 inline void Registers_arm::setVectorRegister(int, v128) {
   _LIBUNWIND_ABORT("ARM vector support not implemented");
 }
+#endif // _LIBUNWIND_TARGET_ARM
+
+
+#if defined(_LIBUNWIND_TARGET_OR1K)
 /// Registers_or1k holds the register state of a thread in an OpenRISC1000
 /// process.
 class _LIBUNWIND_HIDDEN Registers_or1k {
@@ -1745,8 +1758,8 @@
 };
 
 inline Registers_or1k::Registers_or1k(const void *registers) {
-  static_assert(sizeof(Registers_or1k) < sizeof(unw_context_t),
-                    "or1k registers do not fit into unw_context_t");
+  static_assert(check_fit<Registers_or1k, unw_context_t>::does_fit,
+                "or1k registers do not fit into unw_context_t");
   memcpy(&_registers, static_cast<const uint8_t *>(registers),
          sizeof(_registers));
 }
@@ -1893,6 +1906,7 @@
   }
 
 }
+#endif // _LIBUNWIND_TARGET_OR1K
 } // namespace libunwind
 
 #endif // __REGISTERS_HPP__
diff --git a/src/UnwindCursor.hpp b/src/UnwindCursor.hpp
index 9068316..661ef4a 100644
--- a/src/UnwindCursor.hpp
+++ b/src/UnwindCursor.hpp
@@ -481,30 +481,39 @@
     return stepWithCompactEncoding(dummy);
   }
 
+#if defined(_LIBUNWIND_TARGET_X86_64)
   int stepWithCompactEncoding(Registers_x86_64 &) {
     return CompactUnwinder_x86_64<A>::stepWithCompactEncoding(
         _info.format, _info.start_ip, _addressSpace, _registers);
   }
+#endif
 
+#if defined(_LIBUNWIND_TARGET_I386)
   int stepWithCompactEncoding(Registers_x86 &) {
     return CompactUnwinder_x86<A>::stepWithCompactEncoding(
         _info.format, (uint32_t)_info.start_ip, _addressSpace, _registers);
   }
+#endif
 
+#if defined(_LIBUNWIND_TARGET_PPC)
   int stepWithCompactEncoding(Registers_ppc &) {
     return UNW_EINVAL;
   }
+#endif
 
+#if defined(_LIBUNWIND_TARGET_AARCH64)
   int stepWithCompactEncoding(Registers_arm64 &) {
     return CompactUnwinder_arm64<A>::stepWithCompactEncoding(
         _info.format, _info.start_ip, _addressSpace, _registers);
   }
+#endif
 
   bool compactSaysUseDwarf(uint32_t *offset=NULL) const {
     R dummy;
     return compactSaysUseDwarf(dummy, offset);
   }
 
+#if defined(_LIBUNWIND_TARGET_X86_64)
   bool compactSaysUseDwarf(Registers_x86_64 &, uint32_t *offset) const {
     if ((_info.format & UNWIND_X86_64_MODE_MASK) == UNWIND_X86_64_MODE_DWARF) {
       if (offset)
@@ -513,7 +522,9 @@
     }
     return false;
   }
+#endif
 
+#if defined(_LIBUNWIND_TARGET_I386)
   bool compactSaysUseDwarf(Registers_x86 &, uint32_t *offset) const {
     if ((_info.format & UNWIND_X86_MODE_MASK) == UNWIND_X86_MODE_DWARF) {
       if (offset)
@@ -522,11 +533,15 @@
     }
     return false;
   }
+#endif
 
+#if defined(_LIBUNWIND_TARGET_PPC)
   bool compactSaysUseDwarf(Registers_ppc &, uint32_t *) const {
     return true;
   }
+#endif
 
+#if defined(_LIBUNWIND_TARGET_AARCH64)
   bool compactSaysUseDwarf(Registers_arm64 &, uint32_t *offset) const {
     if ((_info.format & UNWIND_ARM64_MODE_MASK) == UNWIND_ARM64_MODE_DWARF) {
       if (offset)
@@ -535,6 +550,7 @@
     }
     return false;
   }
+#endif
 #endif // _LIBUNWIND_SUPPORT_COMPACT_UNWIND
 
 #if _LIBUNWIND_SUPPORT_DWARF_UNWIND
@@ -543,25 +559,35 @@
     return dwarfEncoding(dummy);
   }
 
+#if defined(_LIBUNWIND_TARGET_X86_64)
   compact_unwind_encoding_t dwarfEncoding(Registers_x86_64 &) const {
     return UNWIND_X86_64_MODE_DWARF;
   }
+#endif
 
+#if defined(_LIBUNWIND_TARGET_I386)
   compact_unwind_encoding_t dwarfEncoding(Registers_x86 &) const {
     return UNWIND_X86_MODE_DWARF;
   }
+#endif
 
+#if defined(_LIBUNWIND_TARGET_PPC)
   compact_unwind_encoding_t dwarfEncoding(Registers_ppc &) const {
     return 0;
   }
+#endif
 
+#if defined(_LIBUNWIND_TARGET_AARCH64)
   compact_unwind_encoding_t dwarfEncoding(Registers_arm64 &) const {
     return UNWIND_ARM64_MODE_DWARF;
   }
+#endif
 
+#if defined (_LIBUNWIND_TARGET_OR1K)
   compact_unwind_encoding_t dwarfEncoding(Registers_or1k &) const {
     return 0;
   }
+#endif
 #endif // _LIBUNWIND_SUPPORT_DWARF_UNWIND
 
 
@@ -577,7 +603,7 @@
 UnwindCursor<A, R>::UnwindCursor(unw_context_t *context, A &as)
     : _addressSpace(as), _registers(context), _unwindInfoMissing(false),
       _isSignalFrame(false) {
-  static_assert(sizeof(UnwindCursor<A, R>) < sizeof(unw_cursor_t),
+  static_assert(check_fit<UnwindCursor<A, R>, unw_cursor_t>::does_fit,
                 "UnwindCursor<> does not fit in unw_cursor_t");
   memset(&_info, 0, sizeof(_info));
 }
diff --git a/src/config.h b/src/config.h
index 46bb08a..151030c 100644
--- a/src/config.h
+++ b/src/config.h
@@ -119,5 +119,25 @@
   #define _LIBUNWIND_TRACING_UNWINDING logUnwinding()
 #endif
 
+#ifdef __cplusplus
+// Used to fit UnwindCursor and Registers_xxx types against unw_context_t /
+// unw_cursor_t sized memory blocks.
+#if defined(_LIBUNWIND_IS_NATIVE_ONLY)
+# define COMP_OP ==
+#else
+# define COMP_OP <
+#endif
+template <typename _Type, typename _Mem>
+struct check_fit {
+  template <typename T>
+  struct blk_count {
+    static const uint32_t count =
+      (sizeof(T) + sizeof(uint64_t) - 1) / sizeof(uint64_t);
+  };
+  static const bool does_fit =
+    (blk_count<_Type>::count COMP_OP blk_count<_Mem>::count);
+};
+#undef COMP_OP
+#endif // __cplusplus
 
 #endif // LIBUNWIND_CONFIG_H
diff --git a/src/libunwind.cpp b/src/libunwind.cpp
index f9f32f0..95f2dc0 100644
--- a/src/libunwind.cpp
+++ b/src/libunwind.cpp
@@ -45,30 +45,27 @@
   _LIBUNWIND_TRACE_API("unw_init_local(cursor=%p, context=%p)\n",
                        static_cast<void *>(cursor),
                        static_cast<void *>(context));
-  // Use "placement new" to allocate UnwindCursor in the cursor buffer.
 #if defined(__i386__)
-  new ((void *)cursor) UnwindCursor<LocalAddressSpace, Registers_x86>(
-                                 context, LocalAddressSpace::sThisAddressSpace);
+# define REGISTER_KIND Registers_x86
 #elif defined(__x86_64__)
-  new ((void *)cursor) UnwindCursor<LocalAddressSpace, Registers_x86_64>(
-                                 context, LocalAddressSpace::sThisAddressSpace);
+# define REGISTER_KIND Registers_x86_64
 #elif defined(__ppc__)
-  new ((void *)cursor) UnwindCursor<LocalAddressSpace, Registers_ppc>(
-                                 context, LocalAddressSpace::sThisAddressSpace);
-#elif defined(__arm64__) || defined(__aarch64__)
-  new ((void *)cursor) UnwindCursor<LocalAddressSpace, Registers_arm64>(
-                                 context, LocalAddressSpace::sThisAddressSpace);
+# define REGISTER_KIND Registers_ppc
+#elif defined(__aarch64__)
+# define REGISTER_KIND Registers_arm64
 #elif _LIBUNWIND_ARM_EHABI
-  new ((void *)cursor) UnwindCursor<LocalAddressSpace, Registers_arm>(
-                                 context, LocalAddressSpace::sThisAddressSpace);
+# define REGISTER_KIND Registers_arm
 #elif defined(__or1k__)
-  new ((void *)cursor) UnwindCursor<LocalAddressSpace, Registers_or1k>(
-                                 context, LocalAddressSpace::sThisAddressSpace);
+# define REGISTER_KIND Registers_or1k
 #elif defined(__mips__)
-#warning The MIPS architecture is not supported.
+# warning The MIPS architecture is not supported.
 #else
-#error Architecture not supported
+# error Architecture not supported
 #endif
+  // Use "placement new" to allocate UnwindCursor in the cursor buffer.
+  new ((void *)cursor) UnwindCursor<LocalAddressSpace, REGISTER_KIND>(
+                                 context, LocalAddressSpace::sThisAddressSpace);
+#undef REGISTER_KIND
   AbstractUnwindCursor *co = (AbstractUnwindCursor *)cursor;
   co->setInfoBasedOnIPRegister();