diff --git a/tools/configure/Makefile.mingw b/tools/configure/Makefile.mingw
index 75061c0a15..ed13c1a776 100644
--- a/tools/configure/Makefile.mingw
+++ b/tools/configure/Makefile.mingw
@@ -4,7 +4,7 @@ CONFSRC = $(TOOLSRC)/configure
 
 RAW_PCH       = configure_pch.h
 PCH           = $(RAW_PCH).gch/c++
-DEFINES       = -DUNICODE -DQT_NO_DATASTREAM -DQT_NO_CODECS -DQT_NO_TEXTCODEC -DQT_NO_UNICODETABLES -DQT_LITE_COMPONENT -DQT_NO_COMPRESS -DQT_NO_THREAD -DQT_NO_QOBJECT -DQT_NO_GEOM_VARIANT -D_CRT_SECURE_NO_DEPRECATE -DQT_BOOTSTRAPPED -DQT_BUILD_CONFIGURE -DQT_VERSION_STR=\"$(QTVERSION)\" -DQT_VERSION_MAJOR=$(QT_VERSION_MAJOR) -DQT_VERSION_MINOR=$(QT_VERSION_MINOR) -DQT_VERSION_PATCH=$(QT_VERSION_PATCH)
+DEFINES       = -DUNICODE -DQT_NO_DATASTREAM -DQT_NO_CODECS -DQT_NO_TEXTCODEC -DQT_NO_UNICODETABLES -DQT_LITE_COMPONENT -DQT_NO_COMPRESS -DQT_NO_THREAD -DQT_NO_QOBJECT -DQT_NO_GEOM_VARIANT -D_CRT_SECURE_NO_DEPRECATE -DQT_BOOTSTRAPPED -DQT_BUILD_CONFIGURE -DQT_USE_QSTRINGBUILDER -DQT_VERSION_STR=\"$(QTVERSION)\" -DQT_VERSION_MAJOR=$(QT_VERSION_MAJOR) -DQT_VERSION_MINOR=$(QT_VERSION_MINOR) -DQT_VERSION_PATCH=$(QT_VERSION_PATCH)
 INCPATH       = -I"../../include" -I"../../include/QtCore" -I"../../include/QtCore/$(QTVERSION)" -I"../../include/QtCore/$(QTVERSION)/QtCore" -I"$(TOOLSRC)/shared" -I"$(QTSRC)mkspecs/win32-g++"
 CXXFLAGS_BARE = -std=c++11 -fno-rtti -fno-exceptions -mthreads -Wall -Wextra $(DEFINES) $(INCPATH)
 CXXFLAGS      = -include $(RAW_PCH) $(CXXFLAGS_BARE)
@@ -62,6 +62,7 @@ OBJECTS = \
     qregexp.o \
     qstring.o \
     qstring_compat.o \
+    qstringbuilder.o \
     qstringlist.o \
     qvsnprintf.o \
     qvariant.o \
diff --git a/tools/configure/Makefile.win32 b/tools/configure/Makefile.win32
index 17a758c795..aae3d57ce3 100644
--- a/tools/configure/Makefile.win32
+++ b/tools/configure/Makefile.win32
@@ -2,7 +2,7 @@ CORESRC = $(QTSRC)src\corelib
 TOOLSRC = $(QTSRC)tools
 CONFSRC = $(TOOLSRC)\configure
 
-DEFINES       = -DUNICODE -DQT_NO_CODECS -DQT_NO_TEXTCODEC -DQT_NO_UNICODETABLES -DQT_LITE_COMPONENT -DQT_NO_COMPRESS -DQT_NO_THREAD -DQT_NO_QOBJECT -DQT_NO_GEOM_VARIANT -D_CRT_SECURE_NO_DEPRECATE -DQT_BOOTSTRAPPED -DQT_BUILD_CONFIGURE -DQT_VERSION_STR=\"$(QTVERSION)\" -DQT_VERSION_MAJOR=$(QT_VERSION_MAJOR) -DQT_VERSION_MINOR=$(QT_VERSION_MINOR) -DQT_VERSION_PATCH=$(QT_VERSION_PATCH)
+DEFINES       = -DUNICODE -DQT_NO_CODECS -DQT_NO_TEXTCODEC -DQT_NO_UNICODETABLES -DQT_LITE_COMPONENT -DQT_NO_COMPRESS -DQT_NO_THREAD -DQT_NO_QOBJECT -DQT_NO_GEOM_VARIANT -D_CRT_SECURE_NO_DEPRECATE -DQT_BOOTSTRAPPED -DQT_BUILD_CONFIGURE -DQT_USE_QSTRINGBUILDER -DQT_VERSION_STR=\"$(QTVERSION)\" -DQT_VERSION_MAJOR=$(QT_VERSION_MAJOR) -DQT_VERSION_MINOR=$(QT_VERSION_MINOR) -DQT_VERSION_PATCH=$(QT_VERSION_PATCH)
 INCPATH       = -I"..\..\include" -I"..\..\include\QtCore" -I"..\..\include\QtCore\$(QTVERSION)" -I"..\..\include\QtCore\$(QTVERSION)\QtCore" -I"$(TOOLSRC)\shared" -I"$(QTSRC)mkspecs\win32-msvc2012"
 CXXFLAGS_BARE = -nologo -Zc:wchar_t -W3 -GR -EHsc -w34100 -w34189 -wd4577 $(CFLAGS_CRT) $(EXTRA_CXXFLAGS) $(DEFINES) $(INCPATH)
 !IF ("$(CXX)" != "clang-cl")
@@ -67,6 +67,7 @@ OBJECTS = \
     qregexp.obj \
     qstring.obj \
     qstring_compat.obj \
+    qstringbuilder.obj \
     qstringlist.obj \
     qvsnprintf.obj \
     qvariant.obj \
@@ -141,6 +142,7 @@ qdatetime.obj: $(CORESRC)\tools\qdatetime.cpp $(PCH)
 qmap.obj: $(CORESRC)\tools\qmap.cpp $(PCH)
 qregexp.obj: $(CORESRC)\tools\qregexp.cpp $(PCH)
 qstring.obj: $(CORESRC)\tools\qstring.cpp $(PCH)
+qstringbuilder.obj: $(CORESRC)\tools\qstringbuilder.cpp $(PCH)
 qstringlist.obj: $(CORESRC)\tools\qstringlist.cpp $(PCH)
 qvsnprintf.obj: $(CORESRC)\tools\qvsnprintf.cpp $(PCH)
 qvariant.obj: $(CORESRC)\kernel\qvariant.cpp $(PCH)
diff --git a/tools/configure/configure.pro b/tools/configure/configure.pro
index 939c9ea5ab..f1767e16cd 100644
--- a/tools/configure/configure.pro
+++ b/tools/configure/configure.pro
@@ -3,7 +3,7 @@ DESTDIR   = $$PWD/../..  # build directly in source dir
 
 CONFIG   += console flat stl rtti_off
 CONFIG   -= moc qt
-DEFINES  = UNICODE QT_NO_CODECS QT_NO_TEXTCODEC QT_NO_UNICODETABLES QT_LITE_COMPONENT QT_NO_COMPRESS QT_NO_THREAD QT_NO_QOBJECT QT_NO_GEOM_VARIANT _CRT_SECURE_NO_DEPRECATE
+DEFINES  = UNICODE QT_NO_CODECS QT_NO_TEXTCODEC QT_NO_UNICODETABLES QT_LITE_COMPONENT QT_NO_COMPRESS QT_NO_THREAD QT_NO_QOBJECT QT_NO_GEOM_VARIANT _CRT_SECURE_NO_DEPRECATE QT_USE_QSTRINGBUILDER
 DEFINES  += QT_BOOTSTRAPPED QT_BUILD_CONFIGURE
 
 win32 : LIBS += -lole32 -ladvapi32
@@ -70,6 +70,7 @@ HEADERS  = configureapp.h environment.h tools.h\
            $$QT_SOURCE_TREE/src/corelib/tools/qregexp.h \
            $$QT_SOURCE_TREE/src/corelib/tools/qringbuffer_p.h \
            $$QT_SOURCE_TREE/src/corelib/tools/qstring.h \
+           $$QT_SOURCE_TREE/src/corelib/tools/qstringbuilder.h \
            $$QT_SOURCE_TREE/src/corelib/tools/qstringlist.h \
            $$QT_SOURCE_TREE/src/corelib/tools/qstringmatcher.h \
            $$QT_SOURCE_TREE/src/corelib/tools/qunicodetables_p.h \
@@ -122,6 +123,7 @@ SOURCES  = main.cpp configureapp.cpp environment.cpp tools.cpp \
            $$QT_SOURCE_TREE/src/corelib/tools/qregexp.cpp \
            $$QT_SOURCE_TREE/src/corelib/tools/qringbuffer.cpp \
            $$QT_SOURCE_TREE/src/corelib/tools/qstring.cpp \
+           $$QT_SOURCE_TREE/src/corelib/tools/qstringbuilder.cpp \
            $$QT_SOURCE_TREE/src/corelib/tools/qstring_compat.cpp \
            $$QT_SOURCE_TREE/src/corelib/tools/qstringlist.cpp \
            $$QT_SOURCE_TREE/src/corelib/tools/qvsnprintf.cpp \