diff --git a/CMakeLists.txt b/CMakeLists.txt
index 10df970dff4..e31224ee4ff 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -118,6 +118,9 @@ endif()
 
 qt_build_repo_end()
 
+# This function must be called after the QT_FEATURE_xxx variables have been set up.
+qt_internal_set_up_config_optimizations_like_in_qmake()
+
 if(NOT QT_BUILD_STANDALONE_TESTS AND BUILD_EXAMPLES)
     add_subdirectory(examples)
     if(QT_NO_MAKE_EXAMPLES)
diff --git a/cmake/QtBuildInternals/QtBuildInternalsConfig.cmake b/cmake/QtBuildInternals/QtBuildInternalsConfig.cmake
index 3c8692a903f..63cb264d329 100644
--- a/cmake/QtBuildInternals/QtBuildInternalsConfig.cmake
+++ b/cmake/QtBuildInternals/QtBuildInternalsConfig.cmake
@@ -180,7 +180,9 @@ macro(qt_enable_cmake_languages)
         endif()
     endforeach()
 
-    qt_internal_set_up_config_optimizations_like_in_qmake()
+    if(NOT PROJECT_NAME STREQUAL "QtBase")
+        qt_internal_set_up_config_optimizations_like_in_qmake()
+    endif()
 endmacro()
 
 # Minimum setup required to have any CMakeList.txt build as as a standalone
diff --git a/cmake/QtFlagHandlingHelpers.cmake b/cmake/QtFlagHandlingHelpers.cmake
index cddaa0da39f..29453e29434 100644
--- a/cmake/QtFlagHandlingHelpers.cmake
+++ b/cmake/QtFlagHandlingHelpers.cmake
@@ -356,6 +356,11 @@ function(qt_internal_set_up_config_optimizations_like_in_qmake)
                 endif()
             endif()
 
+            # Debug should get the OPTIMIZE_DEBUG flag if the respective feature is ON.
+            if(config STREQUAL "DEBUG" AND QT_FEATURE_optimize_debug)
+                string(APPEND "${flag_var_name}" " ${QT_CFLAGS_OPTIMIZE_DEBUG}")
+            endif()
+
             # Assign value to the cache entry.
             get_property(help_text CACHE "${flag_var_name}" PROPERTY HELPSTRING)
             set("${flag_var_name}" "${${flag_var_name}}" CACHE STRING "${help_text}" FORCE)
diff --git a/configure.cmake b/configure.cmake
index d870e3a7590..283bb94ed4e 100644
--- a/configure.cmake
+++ b/configure.cmake
@@ -409,6 +409,12 @@ qt_feature("use_lld_linker"
     DISABLE INPUT_linker STREQUAL 'bfd' OR INPUT_linker STREQUAL 'gold'
 )
 qt_feature_config("use_lld_linker" QMAKE_PRIVATE_CONFIG)
+qt_feature("optimize_debug"
+    LABEL "Optimize debug build"
+    AUTODETECT NOT QT_FEATURE_developer_build
+    CONDITION NOT MSVC AND NOT CLANG AND ( QT_FEATURE_debug OR QT_FEATURE_debug_and_release ) AND TEST_optimize_debug
+)
+qt_feature_config("optimize_debug" QMAKE_PRIVATE_CONFIG)
 qt_feature("pkg-config" PUBLIC
     LABEL "Using pkg-config"
     AUTODETECT NOT APPLE AND NOT WIN32
diff --git a/util/cmake/configurejson2cmake.py b/util/cmake/configurejson2cmake.py
index 81181135aca..4edd6cc3d36 100755
--- a/util/cmake/configurejson2cmake.py
+++ b/util/cmake/configurejson2cmake.py
@@ -897,7 +897,6 @@ def get_feature_mapping():
         "incredibuild_xge": None,
         "ltcg": {"autoDetect": "1", "condition": "CMAKE_INTERPROCEDURAL_OPTIMIZATION"},
         "msvc_mp": None,
-        "optimize_debug": None,
         "optimize_size": None,
         "simulator_and_device": {"condition": "UIKIT AND NOT QT_UIKIT_SDK"},
         "pkg-config": {"condition": "PKG_CONFIG_FOUND"},