diff --git a/llvm/cmake/modules/HandleLLVMOptions.cmake b/llvm/cmake/modules/HandleLLVMOptions.cmake
--- a/llvm/cmake/modules/HandleLLVMOptions.cmake
+++ b/llvm/cmake/modules/HandleLLVMOptions.cmake
@@ -690,14 +690,17 @@
   check_cxx_compiler_flag("-Wclass-memaccess" CXX_SUPPORTS_CLASS_MEMACCESS_FLAG)
   append_if(CXX_SUPPORTS_CLASS_MEMACCESS_FLAG "-Wno-class-memaccess" CMAKE_CXX_FLAGS)
 
-  # Disable -Wredundant-move on GCC>=9. GCC wants to remove std::move in code
-  # like "A foo(ConvertibleToA a) { return std::move(a); }", but this code does
-  # not compile (or uses the copy constructor instead) on clang<=3.8. Clang also
-  # has a -Wredundant-move, but it only fires when the types match exactly, so
-  # we can keep it here.
+  # Disable -Wredundant-move and -Wpessimizing-move on GCC>=9. GCC wants to
+  # remove std::move in code like "A foo(ConvertibleToA a) {
+  # return std::move(a); }", but this code does not compile (or uses the copy
+  # constructor instead) on clang<=3.8. Clang also has a -Wredundant-move and
+  # -Wpessimizing-move, but they only fire when the types match exactly, so we
+  # can keep them here.
   if (CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
     check_cxx_compiler_flag("-Wredundant-move" CXX_SUPPORTS_REDUNDANT_MOVE_FLAG)
     append_if(CXX_SUPPORTS_REDUNDANT_MOVE_FLAG "-Wno-redundant-move" CMAKE_CXX_FLAGS)
+    check_cxx_compiler_flag("-Wpessimizing-move" CXX_SUPPORTS_PESSIMIZING_MOVE_FLAG)
+    append_if(CXX_SUPPORTS_PESSIMIZING_MOVE_FLAG "-Wno-pessimizing-move" CMAKE_CXX_FLAGS)
   endif()
 
   # The LLVM libraries have no stable C++ API, so -Wnoexcept-type is not useful.