diff --git a/kde-modules/KDEInstallDirs.cmake b/kde-modules/KDEInstallDirs.cmake
--- a/kde-modules/KDEInstallDirs.cmake
+++ b/kde-modules/KDEInstallDirs.cmake
@@ -289,6 +289,8 @@
     MANDIR
     DOCDIR)
 
+set(_gnu_install_special_vars LOCALSTATEDIR SYSCONFDIR RUNSTATEDIR)
+
 # Macro for variables that are relative to another variable. We store an empty
 # value in the cache (for documentation/GUI cache editor purposes), and store
 # the default value in a local variable. If the cache variable is ever set to
@@ -365,12 +367,24 @@
         if(_cmakename_is_deprecated AND NOT CMAKE_VERSION VERSION_LESS 3.0.0)
             message(DEPRECATION "${_cmakename} is deprecated, use KDE_INSTALL_${varname} instead.")
         endif()
-        # The CMAKE_ name was given (probably on the command line): move
+        # The CMAKE_ name was given (probably by GNUInstallDirs or on the command line): move
         # it to the new name
-        set(KDE_INSTALL_${varname} "${${_cmakename}}"
-            CACHE PATH
-                  "${docstring} (${_docpath})"
-                  FORCE)
+        #
+        # In special cases defined by GNU Coding Standards and Filesystem Hierarchy Standard,
+        # paths in CMAKE_INSTALL_xDIR shouldn't be resolved as relative to CMAKE_INSTALL_PREFIX.
+        # Reuse here resolving logic from GNUInstallDirs.
+        list(FIND _gnu_install_special_vars "${varname}" _vars_list_offset)
+        if (CMAKE_INSTALL_FULL_${varname} AND (CMAKE_INSTALL_PREFIX STREQUAL "/usr" OR CMAKE_INSTALL_PREFIX MATCHES "^/opt/.") AND NOT _vars_list_offset EQUAL -1)
+             set(KDE_INSTALL_${varname} "${CMAKE_INSTALL_FULL_${varname}}"
+                 CACHE PATH
+                     "${docstring} (${_docpath})"
+                     FORCE)
+         else()
+            set(KDE_INSTALL_${varname} "${${_cmakename}}"
+                CACHE PATH
+                    "${docstring} (${_docpath})"
+                    FORCE)
+         endif()
     else()
         # insert an empty value into the cache, indicating the default
         # should be used (including compatibility vars above)
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -135,6 +135,62 @@
 add_test_variant(KDEInstallDirsTest.vars_in_sync_cmake_arg
                  KDEInstallDirsTest.vars_in_sync dummy)
 
+set(KDEInstallDirsTest.vars_in_sync_cmake_arg_gnu_usr_EXTRA_OPTIONS
+	--build-options -DCMAKE_INSTALL_PREFIX=/usr
+                    -DCONFDIR_expected_value=/etc/xdg
+                    -DFULL_CONFDIR_expected_value=/etc/xdg
+                    -DLOCALSTATEDIR_expected_value=/var
+                    -DFULL_LOCALSTATEDIR_expected_value=/var
+                    -DINCLUDEDIR_expected_value=include
+                    -DFULL_INCLUDEDIR_expected_value=/usr/include
+                    -Dinclude_gnuinstalldirs=TRUE
+                    -DCMAKE_WARN_DEPRECATED=TRUE
+    )
+add_test_variant(KDEInstallDirsTest.vars_in_sync_cmake_arg_gnu_usr
+                 KDEInstallDirsTest.vars_in_sync dummy)
+
+set(KDEInstallDirsTest.vars_in_sync_cmake_arg_gnu_usrlocal_EXTRA_OPTIONS
+	--build-options -DCMAKE_INSTALL_PREFIX=/usr/local
+                    -DCONFDIR_expected_value=etc/xdg
+                    -DFULL_CONFDIR_expected_value=/usr/local/etc/xdg
+                    -DLOCALSTATEDIR_expected_value=var
+                    -DFULL_LOCALSTATEDIR_expected_value=/usr/local/var
+                    -DINCLUDEDIR_expected_value=include
+                    -DFULL_INCLUDEDIR_expected_value=/usr/local/include
+                    -Dinclude_gnuinstalldirs=TRUE
+                    -DCMAKE_WARN_DEPRECATED=TRUE
+    )
+add_test_variant(KDEInstallDirsTest.vars_in_sync_cmake_arg_gnu_usrlocal
+                 KDEInstallDirsTest.vars_in_sync dummy)
+
+set(KDEInstallDirsTest.vars_in_sync_cmake_arg_gnu_optkde_EXTRA_OPTIONS
+	--build-options -DCMAKE_INSTALL_PREFIX=/opt/kde
+                    -DCONFDIR_expected_value=/etc/opt/kde/xdg
+                    -DFULL_CONFDIR_expected_value=/etc/opt/kde/xdg
+                    -DLOCALSTATEDIR_expected_value=/var/opt/kde
+                    -DFULL_LOCALSTATEDIR_expected_value=/var/opt/kde
+                    -DINCLUDEDIR_expected_value=include
+                    -DFULL_INCLUDEDIR_expected_value=/opt/kde/include
+                    -Dinclude_gnuinstalldirs=TRUE
+                    -DCMAKE_WARN_DEPRECATED=TRUE
+    )
+add_test_variant(KDEInstallDirsTest.vars_in_sync_cmake_arg_gnu_optkde
+                 KDEInstallDirsTest.vars_in_sync dummy)
+
+set(KDEInstallDirsTest.vars_in_sync_cmake_arg_gnu_root_EXTRA_OPTIONS
+	--build-options -DCMAKE_INSTALL_PREFIX=/
+                    -DCONFDIR_expected_value=etc/xdg
+                    -DFULL_CONFDIR_expected_value=//etc/xdg
+                    -DLOCALSTATEDIR_expected_value=var
+                    -DFULL_LOCALSTATEDIR_expected_value=//var
+                    -DINCLUDEDIR_expected_value=usr/include
+                    -DFULL_INCLUDEDIR_expected_value=//usr/include
+                    -Dinclude_gnuinstalldirs=TRUE
+                    -DCMAKE_WARN_DEPRECATED=TRUE
+    )
+add_test_variant(KDEInstallDirsTest.vars_in_sync_cmake_arg_gnu_root
+                 KDEInstallDirsTest.vars_in_sync dummy)
+
 set(KDEInstallDirsTest.vars_in_sync_oldstyle_arg_EXTRA_OPTIONS
     --build-options -DBIN_INSTALL_DIR=altbin
                     -DBINDIR_expected_value=altbin
diff --git a/tests/KDEInstallDirsTest/vars_in_sync/CMakeLists.txt b/tests/KDEInstallDirsTest/vars_in_sync/CMakeLists.txt
--- a/tests/KDEInstallDirsTest/vars_in_sync/CMakeLists.txt
+++ b/tests/KDEInstallDirsTest/vars_in_sync/CMakeLists.txt
@@ -4,6 +4,9 @@
 set(ECM_KDE_MODULE_DIR ${CMAKE_CURRENT_SOURCE_DIR}/../../../kde-modules)
 set(ECM_MODULE_DIR ${CMAKE_CURRENT_SOURCE_DIR}/../../../modules)
 set(CMAKE_MODULE_PATH "${ECM_KDE_MODULE_DIR}")
+if (include_gnuinstalldirs)
+    include(GNUInstallDirs)
+endif()
 include(KDEInstallDirs)
 
 include(../var_list.cmake)
@@ -15,6 +18,9 @@
         assert_vars_strequal(KDE_INSTALL_${suffix} ${suffix}_expected_value)
     endif()
     assert_var_defined(KDE_INSTALL_FULL_${suffix})
+    if(DEFINED FULL_${suffix}_expected_value)
+        assert_vars_strequal(KDE_INSTALL_FULL_${suffix} FULL_${suffix}_expected_value)
+    endif()
 
     if(should_set_CMAKE_INSTALL_${suffix})
         assert_vars_strequal(CMAKE_INSTALL_${suffix} KDE_INSTALL_${suffix})