diff --git a/configure b/configure
index 100c3db0d25..82df73fb1b1 100755
--- a/configure
+++ b/configure
@@ -283,23 +283,6 @@ getQMakeConf()
     getSingleQMakeVariable "$1" "$specvals"
 }
 
-resolveDeviceMkspec()
-{
-    result=$(find "$relpath/mkspecs/devices/" -type d -name "*$1*" | sed "s,^$relpath/mkspecs/,,")
-    match_count=$(echo "$result" | wc -w)
-    if [ "$match_count" -gt 1 ]; then
-        echo >&2 "Error: Multiple matches for device '$1'. Candidates are:"
-        tabbed_result=$(echo "$result" | sed 's,^,    ,')
-        echo >&2 "$tabbed_result"
-        echo "undefined"
-    elif [ "$match_count" -eq 0 ]; then
-        echo >&2 "Error: No device matching '$1'"
-        echo "undefined"
-    else
-        echo "$result"
-    fi
-}
-
 #-------------------------------------------------------------------------------
 # operating system detection
 #-------------------------------------------------------------------------------
@@ -366,14 +349,6 @@ unset QTDIR
 
 # initalize internal variables
 CFG_RELEASE_TOOLS=no
-
-XPLATFORM=              # This seems to be the QMAKESPEC, like "linux-g++"
-XPLATFORM_MAC=no        # Whether target platform is macOS, iOS, tvOS, or watchOS
-XPLATFORM_IOS=no        # Whether target platform is iOS
-XPLATFORM_TVOS=no       # Whether target platform is tvOS
-XPLATFORM_WATCHOS=no    # Whether target platform is watchOS
-XPLATFORM_ANDROID=no
-XPLATFORM_MINGW=no      # Whether target platform is MinGW (win32-g++*)
 PLATFORM=
 OPT_SHADOW=maybe
 OPT_VERBOSE=no
@@ -503,13 +478,6 @@ while [ "$#" -gt 0 ]; do
     platform)
         PLATFORM="$VAL"
         ;;
-    xplatform)
-        XPLATFORM="$VAL"
-        ;;
-    device)
-        XPLATFORM=`resolveDeviceMkspec $VAL`
-        [ "$XPLATFORM" = "undefined" ] && exit 101
-        ;;
     optimized-qmake|optimized-tools)
         if [ "$VAL" = "yes" ] || [ "$VAL" = "no" ]; then
             CFG_RELEASE_TOOLS="$VAL"
@@ -711,44 +679,6 @@ if [ -z "$PLATFORM" ]; then
     esac
 fi
 
-[ -z "$XPLATFORM" ] && XPLATFORM="$PLATFORM"
-
-case "$XPLATFORM" in
-    *win32-g++*)
-        XPLATFORM_MINGW=yes
-        ;;
-    *qnx-*)
-        ;;
-    *haiku-*)
-        ;;
-    *ios*)
-        XPLATFORM_MAC=yes
-        XPLATFORM_IOS=yes
-        ;;
-    *tvos*)
-        XPLATFORM_MAC=yes
-        XPLATFORM_TVOS=yes
-        ;;
-    *watchos*)
-        XPLATFORM_MAC=yes
-        XPLATFORM_WATCHOS=yes
-        ;;
-    *macx*)
-        XPLATFORM_MAC=yes
-        ;;
-    *integrity*)
-        ;;
-    # XPLATFORM_ANDROID should not be set for unsupported/android-g++
-    *unsupported*)
-        ;;
-    *android-g++*)
-        XPLATFORM_ANDROID=g++
-        ;;
-    *android-clang*)
-        XPLATFORM_ANDROID=clang
-        ;;
-esac
-
 #-------------------------------------------------------------------------------
 # command line and environment validation
 #-------------------------------------------------------------------------------
@@ -758,14 +688,9 @@ if [ -d "$PLATFORM" ]; then
 else
   QMAKESPEC="$relpath/mkspecs/${PLATFORM}"
 fi
-if [ -d "$XPLATFORM" ]; then
-  XQMAKESPEC="$XPLATFORM"
-else
-  XQMAKESPEC="$relpath/mkspecs/${XPLATFORM}"
-fi
 
 if [ "$BUILD_ON_MAC" = "yes" ]; then
-   if [ `basename $QMAKESPEC` = "macx-xcode" ] || [ `basename $XQMAKESPEC` = "macx-xcode" ]; then
+   if [ `basename $QMAKESPEC` = "macx-xcode" ]; then
       echo >&2
       echo "   Platform 'macx-xcode' should not be used when building Qt/Mac." >&2
       echo "   Please build Qt/Mac with 'macx-clang' or 'macx-g++', then use" >&2
@@ -787,26 +712,6 @@ if [ '!' -d "$QMAKESPEC" ]; then
     echo
     exit 2
 fi
-if [ '!' -d "$XQMAKESPEC" ]; then
-    echo
-    echo "   The specified system/compiler is not supported:"
-    echo
-    echo "      $XQMAKESPEC"
-    echo
-    echo "   Please see the README file for a complete list."
-    echo
-    exit 2
-fi
-if [ '!' -f "${XQMAKESPEC}/qplatformdefs.h" ]; then
-    echo
-    echo "   The specified system/compiler port is not complete:"
-    echo
-    echo "      $XQMAKESPEC/qplatformdefs.h"
-    echo
-    echo "   Please information use the contact form at http://www.qt.io/contact-us"
-    echo
-    exit 2
-fi
 
 #-------------------------------------------------------------------------------
 # build tree initialization
@@ -980,7 +885,7 @@ cat > "$QTCONFFILE" <<EOF
 [EffectivePaths]
 Prefix=..
 [Paths]
-TargetSpec=$XPLATFORM
+TargetSpec=dummy
 HostSpec=$PLATFORM
 EOF
 if [ x"$relpath" != x"$outpath" ]; then
diff --git a/configure.json b/configure.json
index 59358180d0b..77f956ed1a1 100644
--- a/configure.json
+++ b/configure.json
@@ -423,7 +423,7 @@
 
     "features": {
         "prepare": {
-            "output": [ "prepareOptions", "preparePaths" ]
+            "output": [ "prepareSpec", "prepareOptions", "preparePaths" ]
         },
         "machineTuple": {
             "condition": "!config.linux || config.android || tests.machineTuple",
@@ -983,6 +983,11 @@
     },
 
     "earlyReport": [
+        {
+            "type": "fatal",
+            "condition": "input.xplatform != '' && input.device != ''",
+            "message": "Cannot specify both -xplatform and -device."
+        },
         {
             "condition": "!features.prepare",
             "comment": "This is not an actual report - instead, it activates the early setup."
diff --git a/configure.pri b/configure.pri
index b8e338bb545..92020abbbba 100644
--- a/configure.pri
+++ b/configure.pri
@@ -476,6 +476,37 @@ defineTest(reloadSpec) {
     }
 }
 
+defineTest(qtConfOutput_prepareSpec) {
+    device = $$eval(config.input.device)
+    !isEmpty(device) {
+        devices = $$files($$[QT_HOST_DATA/src]/mkspecs/devices/*$$device*)
+        isEmpty(devices): \
+            qtConfFatalError("No device matching '$$device'.")
+        !count(devices, 1) {
+            err = "Multiple matches for device '$$device'. Candidates are:"
+            for (d, devices): \
+                err += "    $$basename(d)"
+            qtConfFatalError($$err)
+        }
+        XSPEC = $$relative_path($$devices, $$[QT_HOST_DATA/src]/mkspecs)
+    }
+    xspec = $$eval(config.input.xplatform)
+    !isEmpty(xspec) {
+        !exists($$[QT_HOST_DATA/src]/mkspecs/$$xspec/qmake.conf): \
+            qtConfFatalError("Invalid target platform '$$xspec'.")
+        XSPEC = $$xspec
+    }
+    isEmpty(XSPEC): \
+        XSPEC = $$[QMAKE_SPEC]
+    export(XSPEC)
+    QMAKESPEC = $$[QT_HOST_DATA/src]/mkspecs/$$XSPEC
+    export(QMAKESPEC)
+
+    # deviceOptions() below contains conditionals coming form the spec,
+    # so this cannot be delayed for a batch reload.
+    reloadSpec()
+}
+
 defineTest(qtConfOutput_prepareOptions) {
     $${currentConfig}.output.devicePro += \
         $$replace(config.input.device-option, "^([^=]+) *= *(.*)$", "\\1 = \\2")
@@ -649,7 +680,7 @@ defineReplace(printHostPaths) {
         $$printInstallPath(HostLibraries, hostlibdir, lib) \
         $$printInstallPath(HostData, hostdatadir, .) \
         "Sysroot=$$config.input.sysroot" \
-        "TargetSpec=$$[QMAKE_XSPEC]" \
+        "TargetSpec=$$XSPEC" \
         "HostSpec=$$[QMAKE_SPEC]"
     return($$ret)
 }
diff --git a/mkspecs/dummy/qmake.conf b/mkspecs/dummy/qmake.conf
new file mode 100644
index 00000000000..7077fe6345c
--- /dev/null
+++ b/mkspecs/dummy/qmake.conf
@@ -0,0 +1,8 @@
+#
+# Minimal qmake configuration qt_configure.prf is run with.
+#
+
+# Make spec_post.prf happy.
+MAKEFILE_GENERATOR = DUMMY
+QMAKE_PLATFORM = dummy_platform
+QMAKE_COMPILER = dummy_compiler
diff --git a/mkspecs/features/qt_configure.prf b/mkspecs/features/qt_configure.prf
index b7b4e1f994a..41bd75c45d3 100644
--- a/mkspecs/features/qt_configure.prf
+++ b/mkspecs/features/qt_configure.prf
@@ -1768,6 +1768,14 @@ QMAKE_SAVED_ARGS = $$QMAKE_EXTRA_ARGS
 QMAKE_REDO_CONFIG = false
 qtConfParseCommandLine()
 
+for (currentConfig, allConfigs) {
+    qtConfSetModuleName()
+    qtConfSetupModuleOutputs()
+    # do early checks, mainly to validate the command line
+    qtConfProcessEarlyChecks()
+}
+qtConfCheckErrors()
+
 !isEmpty(_QMAKE_SUPER_CACHE_): \
     QMAKE_CONFIG_CACHE = $$dirname(_QMAKE_SUPER_CACHE_)/config.cache
 else: \
@@ -1790,14 +1798,6 @@ QMAKE_CONFIG_LOG = $$OUT_PWD/config.log
 !equals(QMAKE_CONFIG_CACHE_USE, all): \
     write_file($$QMAKE_CONFIG_LOG, "")
 
-for (currentConfig, allConfigs) {
-    qtConfSetModuleName()
-    qtConfSetupModuleOutputs()
-    # do early checks, mainly to validate the command line
-    qtConfProcessEarlyChecks()
-}
-qtConfCheckErrors()
-
 CONFIG += qt_conf_tests_allowed
 logn()
 logn("Running configuration tests...")
diff --git a/tools/configure/configureapp.cpp b/tools/configure/configureapp.cpp
index 373fc89090e..2ffec0707fe 100644
--- a/tools/configure/configureapp.cpp
+++ b/tools/configure/configureapp.cpp
@@ -130,20 +130,6 @@ void Configure::parseCmdLine()
         }
     }
 
-    // Then look for XQMAKESPEC
-    bool isDeviceMkspec = false;
-    for (int j = 0 ; j < argCount; ++j)
-    {
-        if ((configCmdLine.at(j) == "-xplatform") || (configCmdLine.at(j) == "-device")) {
-            isDeviceMkspec = (configCmdLine.at(j) == "-device");
-            ++j;
-            if (j == argCount)
-                break;
-            dictionary["XQMAKESPEC"] = configCmdLine.at(j);
-            break;
-        }
-    }
-
     for (; i<configCmdLine.size(); ++i) {
         if (configCmdLine.at(i) == "-platform") {
             ++i;
@@ -151,10 +137,6 @@ void Configure::parseCmdLine()
                 break;
             dictionary[ "QMAKESPEC" ] = configCmdLine.at(i);
         dictionary[ "QMAKESPEC_FROM" ] = "commandline";
-        } else if (configCmdLine.at(i) == "-xplatform"
-                || configCmdLine.at(i) == "-device") {
-            ++i;
-            // do nothing
         }
 
         else if (configCmdLine.at(i) == "-no-syncqt")
@@ -207,34 +189,6 @@ void Configure::parseCmdLine()
             dictionary[ "QMAKEMAKEFILE" ] = "Makefile.win32";
         }
     }
-
-    if (isDeviceMkspec) {
-        const QStringList devices = mkspecs.filter("devices/", Qt::CaseInsensitive);
-        const QStringList family = devices.filter(dictionary["XQMAKESPEC"], Qt::CaseInsensitive);
-
-        if (family.isEmpty()) {
-            dictionary[ "DONE" ] = "error";
-            cout << "Error: No device matching '" << dictionary["XQMAKESPEC"] << "'." << endl;
-        } else if (family.size() > 1) {
-            dictionary[ "DONE" ] = "error";
-
-            cout << "Error: Multiple matches for device '" << dictionary["XQMAKESPEC"] << "'. Candidates are:" << endl;
-
-            foreach (const QString &device, family)
-                cout << "\t* " << device << endl;
-        } else {
-            Q_ASSERT(family.size() == 1);
-            dictionary["XQMAKESPEC"] = family.at(0);
-        }
-
-    } else {
-        // Ensure that -spec (XQMAKESPEC) exists in the mkspecs folder as well
-        if (dictionary.contains("XQMAKESPEC") &&
-                !mkspecs.contains(dictionary["XQMAKESPEC"], Qt::CaseInsensitive)) {
-            dictionary[ "DONE" ] = "error";
-            cout << "Invalid option \"" << dictionary["XQMAKESPEC"] << "\" for -xplatform." << endl;
-        }
-    }
 }
 
 void Configure::generateHeaders()
@@ -361,8 +315,7 @@ void Configure::buildQmake()
         confStream << "[EffectivePaths]" << endl
                    << "Prefix=.." << endl
                    << "[Paths]" << endl
-                   << "TargetSpec=" << (dictionary.contains("XQMAKESPEC")
-                                        ? dictionary["XQMAKESPEC"] : dictionary["QMAKESPEC"]) << endl
+                   << "TargetSpec=dummy" << endl
                    << "HostSpec=" << dictionary["QMAKESPEC"] << endl;
         if (sourcePath != buildPath)
             confStream << "[EffectiveSourcePaths]" << endl