diff --git a/libcxx/lib/abi/CMakeLists.txt b/libcxx/lib/abi/CMakeLists.txt
index 2b3551d7f67f6..e39bad0c7ca4f 100644
--- a/libcxx/lib/abi/CMakeLists.txt
+++ b/libcxx/lib/abi/CMakeLists.txt
@@ -16,7 +16,6 @@ endif()
 # Detect if we are building in the same configuration used to generate
 # the abilist files.
 set(ABILIST_FILE "${CMAKE_CURRENT_LIST_DIR}/${GENERIC_TARGET_TRIPLE}.v${LIBCXX_ABI_VERSION}.abilist")
-set(SYMDIFF_EXE "${LIBCXX_SOURCE_DIR}/utils/sym_diff.py")
 if (EXISTS "${ABILIST_FILE}"
     AND TARGET cxx_shared
     AND ("${LIBCXX_CXX_ABI_LIBNAME}" STREQUAL "libcxxabi" OR
@@ -25,8 +24,10 @@ if (EXISTS "${ABILIST_FILE}"
     AND LIBCXX_ENABLE_EXCEPTIONS
     AND NOT LIBCXX_ENABLE_NEW_DELETE_DEFINITIONS)
     add_custom_target(check-cxx-abilist
-            ${SYMDIFF_EXE} --only-stdlib-symbols --strict ${ABILIST_FILE}
-            $<TARGET_SONAME_FILE:cxx_shared>
+            ${Python3_EXECUTABLE} "${LIBCXX_SOURCE_DIR}/utils/sym_diff.py"
+                --only-stdlib-symbols
+                --strict ${ABILIST_FILE}
+                $<TARGET_SONAME_FILE:cxx_shared>
             DEPENDS cxx_shared
             COMMENT "Testing ABI compatibility...")
 else()
diff --git a/libcxx/utils/libcxx/sym_check/util.py b/libcxx/utils/libcxx/sym_check/util.py
index 4b04ac4dfe2d6..13f09d4b214f4 100644
--- a/libcxx/utils/libcxx/sym_check/util.py
+++ b/libcxx/utils/libcxx/sym_check/util.py
@@ -83,12 +83,12 @@ def is_mach_o(filename):
     with open(filename, 'rb') as f:
         magic_bytes = f.read(4)
     return magic_bytes in [
-        '\xfe\xed\xfa\xce',  # MH_MAGIC
-        '\xce\xfa\xed\xfe',  # MH_CIGAM
-        '\xfe\xed\xfa\xcf',  # MH_MAGIC_64
-        '\xcf\xfa\xed\xfe',  # MH_CIGAM_64
-        '\xca\xfe\xba\xbe',  # FAT_MAGIC
-        '\xbe\xba\xfe\xca'   # FAT_CIGAM
+        b'\xfe\xed\xfa\xce',  # MH_MAGIC
+        b'\xce\xfa\xed\xfe',  # MH_CIGAM
+        b'\xfe\xed\xfa\xcf',  # MH_MAGIC_64
+        b'\xcf\xfa\xed\xfe',  # MH_CIGAM_64
+        b'\xca\xfe\xba\xbe',  # FAT_MAGIC
+        b'\xbe\xba\xfe\xca'   # FAT_CIGAM
     ]
 
 
diff --git a/libcxxabi/src/CMakeLists.txt b/libcxxabi/src/CMakeLists.txt
index 7093cef60abc6..ec88a1e4d27d6 100644
--- a/libcxxabi/src/CMakeLists.txt
+++ b/libcxxabi/src/CMakeLists.txt
@@ -285,7 +285,7 @@ if (LIBCXXABI_ENABLE_STATIC)
   # Merge the libc++abi.a and libunwind.a into one.
   if(LIBCXXABI_USE_LLVM_UNWINDER AND LIBCXXABI_STATICALLY_LINK_UNWINDER_IN_STATIC_LIBRARY)
     add_custom_command(TARGET cxxabi_static POST_BUILD
-      COMMAND ${PYTHON_EXECUTABLE} ${LIBCXXABI_LIBCXX_PATH}/utils/merge_archives.py
+      COMMAND ${Python3_EXECUTABLE} ${LIBCXXABI_LIBCXX_PATH}/utils/merge_archives.py
       ARGS
         -o "$<TARGET_LINKER_FILE:cxxabi_static>"
         --ar "${CMAKE_AR}"