diff --git a/src/plugins/android/androidconfigurations.cpp b/src/plugins/android/androidconfigurations.cpp
index 889d1a46309..ee4c7198eec 100644
--- a/src/plugins/android/androidconfigurations.cpp
+++ b/src/plugins/android/androidconfigurations.cpp
@@ -1233,21 +1233,15 @@ static bool equalKits(Kit *a, Kit *b)
 
 void AndroidConfigurations::registerNewToolChains()
 {
-    QList<ToolChain *> existingToolChains = ToolChainManager::toolChains();
-    QList<ToolChain *> toolchains = AndroidToolChainFactory::createToolChainsForNdk(AndroidConfigurations::currentConfig().ndkLocation());
-    foreach (ToolChain *tc, toolchains) {
-        bool found = false;
-        for (int i = 0; i < existingToolChains.count(); ++i) {
-            if (*(existingToolChains.at(i)) == *tc) {
-                found = true;
-                break;
-            }
-        }
-        if (found)
-            delete tc;
-        else
+    const QList<ToolChain *> existingAndroidToolChains
+            = Utils::filtered(ToolChainManager::toolChains(),
+                              Utils::equal(&ToolChain::typeId, Core::Id(Constants::ANDROID_TOOLCHAIN_ID)));
+
+    const QList<ToolChain *> newToolchains
+            = AndroidToolChainFactory::autodetectToolChainsForNdk(AndroidConfigurations::currentConfig().ndkLocation(),
+                                                                  existingAndroidToolChains);
+    foreach (ToolChain *tc, newToolchains)
             ToolChainManager::registerToolChain(tc);
-    }
 }
 
 void AndroidConfigurations::removeOldToolChains()
diff --git a/src/plugins/android/androidtoolchain.cpp b/src/plugins/android/androidtoolchain.cpp
index ab7f362c586..76b1d7bad3f 100644
--- a/src/plugins/android/androidtoolchain.cpp
+++ b/src/plugins/android/androidtoolchain.cpp
@@ -42,6 +42,7 @@
 #include <projectexplorer/toolchainmanager.h>
 #include <projectexplorer/projectexplorer.h>
 
+#include <utils/algorithm.h>
 #include <utils/environment.h>
 #include <utils/hostosinfo.h>
 
@@ -260,8 +261,7 @@ AndroidToolChainFactory::AndroidToolChainFactory()
 
 QList<ToolChain *> AndroidToolChainFactory::autoDetect(const QList<ToolChain *> &alreadyKnown)
 {
-    Q_UNUSED(alreadyKnown);
-    return createToolChainsForNdk(AndroidConfigurations::currentConfig().ndkLocation());
+    return autodetectToolChainsForNdk(AndroidConfigurations::currentConfig().ndkLocation(), alreadyKnown);
 }
 
 bool AndroidToolChainFactory::canRestore(const QVariantMap &data)
@@ -352,11 +352,23 @@ bool AndroidToolChainFactory::versionCompareLess(AndroidToolChain *atc, AndroidT
     return versionCompareLess(a, b);
 }
 
-QList<ToolChain *> AndroidToolChainFactory::createToolChainsForNdk(const FileName &ndkPath)
+static AndroidToolChain *findToolChain(Utils::FileName &compilerPath, const QList<ToolChain *> &alreadyKnown)
+{
+    return static_cast<AndroidToolChain *>(
+                Utils::findOrDefault(alreadyKnown, [compilerPath](ToolChain *tc) {
+                                                       return tc->compilerCommand() == compilerPath
+                                                           && tc->typeId() == Constants::ANDROID_TOOLCHAIN_ID;
+                                                   }));
+}
+
+QList<ToolChain *>
+AndroidToolChainFactory::autodetectToolChainsForNdk(const FileName &ndkPath,
+                                                    const QList<ToolChain *> &alreadyKnown)
 {
     QList<ToolChain *> result;
     if (ndkPath.isEmpty())
         return result;
+
     QRegExp versionRegExp(NDKGccVersionRegExp);
     FileName path = ndkPath;
     QDirIterator it(path.appendPath(QLatin1String("toolchains")).toString(),
@@ -373,13 +385,16 @@ QList<ToolChain *> AndroidToolChainFactory::createToolChainsForNdk(const FileNam
         Abi abi = AndroidConfig::abiForToolChainPrefix(platform);
         if (abi.architecture() == Abi::UnknownArchitecture) // e.g. mipsel which is not yet supported
             continue;
-        AndroidToolChain *tc = new AndroidToolChain(abi, version, ToolChain::AutoDetection);
         FileName compilerPath = AndroidConfigurations::currentConfig().gccPath(abi, version);
-        tc->resetToolChain(compilerPath);
+
+        AndroidToolChain *tc = findToolChain(compilerPath, alreadyKnown);
+        if (!tc) {
+            tc = new AndroidToolChain(abi, version, ToolChain::AutoDetection);
+            tc->resetToolChain(compilerPath);
+        }
         result.append(tc);
 
-        QHash<Abi, AndroidToolChain *>::const_iterator it
-                = newestToolChainForArch.constFind(abi);
+        auto it = newestToolChainForArch.constFind(abi);
         if (it == newestToolChainForArch.constEnd())
             newestToolChainForArch.insert(abi, tc);
         else if (versionCompareLess(it.value(), tc))
@@ -388,8 +403,7 @@ QList<ToolChain *> AndroidToolChainFactory::createToolChainsForNdk(const FileNam
 
     foreach (ToolChain *tc, result) {
         AndroidToolChain *atc = static_cast<AndroidToolChain *>(tc);
-        if (newestToolChainForArch.value(atc->targetAbi()) != atc)
-            atc->setSecondaryToolChain(true);
+        atc->setSecondaryToolChain(newestToolChainForArch.value(atc->targetAbi()) != atc);
     }
 
     return result;
diff --git a/src/plugins/android/androidtoolchain.h b/src/plugins/android/androidtoolchain.h
index a17bfb810e0..dae082dcc41 100644
--- a/src/plugins/android/androidtoolchain.h
+++ b/src/plugins/android/androidtoolchain.h
@@ -113,7 +113,9 @@ public:
         QString version;
     };
 
-    static QList<ProjectExplorer::ToolChain *> createToolChainsForNdk(const Utils::FileName &ndkPath);
+    static QList<ProjectExplorer::ToolChain *>
+    autodetectToolChainsForNdk(const Utils::FileName &ndkPath,
+                               const QList<ProjectExplorer::ToolChain *> &alreadyKnown);
     static QList<AndroidToolChainInformation> toolchainPathsForNdk(const Utils::FileName &ndkPath);
 
     static QList<int> versionNumberFromString(const QString &version);
diff --git a/src/plugins/ios/iosconfigurations.cpp b/src/plugins/ios/iosconfigurations.cpp
index 362160018ac..9bf56c2a6ee 100644
--- a/src/plugins/ios/iosconfigurations.cpp
+++ b/src/plugins/ios/iosconfigurations.cpp
@@ -375,10 +375,10 @@ QList<ToolChain *> IosToolChainFactory::autoDetect(const QList<ToolChain *> &exi
     foreach (const Platform &platform, platforms) {
         ClangToolChain *toolChain = findToolChainForPlatform(platform, existingClangToolChains);
         if (!toolChain) {
-            ClangToolChain *newToolChain = createToolChain(platform);
-            toolChains.append(newToolChain);
-            existingClangToolChains.append(newToolChain);
+            toolChain = createToolChain(platform);
+            existingClangToolChains.append(toolChain);
         }
+        toolChains.append(toolChain);
     }
     return Utils::transform(toolChains, [](ClangToolChain *tc) -> ToolChain * { return tc; });
 }
diff --git a/src/plugins/projectexplorer/gcctoolchain.cpp b/src/plugins/projectexplorer/gcctoolchain.cpp
index f5da4d4dacb..22675549e18 100644
--- a/src/plugins/projectexplorer/gcctoolchain.cpp
+++ b/src/plugins/projectexplorer/gcctoolchain.cpp
@@ -819,7 +819,8 @@ QList<ToolChain *> GccToolChainFactory::autoDetectToolchains(const QString &comp
     if (compilerPath.isEmpty())
         return result;
 
-    if (Utils::findOrDefault(alreadyKnown, Utils::equal(&ToolChain::compilerCommand, compilerPath)))
+    result = Utils::filtered(alreadyKnown, Utils::equal(&ToolChain::compilerCommand, compilerPath));
+    if (!result.isEmpty())
         return result;
 
     GccToolChain::addCommandPathToEnvironment(compilerPath, systemEnvironment);
diff --git a/src/plugins/projectexplorer/msvctoolchain.cpp b/src/plugins/projectexplorer/msvctoolchain.cpp
index 08bd7954c21..16633ecc4e2 100644
--- a/src/plugins/projectexplorer/msvctoolchain.cpp
+++ b/src/plugins/projectexplorer/msvctoolchain.cpp
@@ -33,6 +33,7 @@
 #include "msvcparser.h"
 #include "projectexplorerconstants.h"
 
+#include <utils/algorithm.h>
 #include <utils/synchronousprocess.h>
 #include <utils/winutils.h>
 #include <utils/qtcassert.h>
@@ -526,9 +527,26 @@ QString MsvcToolChainFactory::vcVarsBatFor(const QString &basePath, MsvcToolChai
     return vcVarsBatFor(basePath, platformName(platform));
 }
 
+static ToolChain *findOrCreateToolChain(const QList<ToolChain *> &alreadyKnown,
+                                        const QString &name, const Abi &abi,
+                                        const QString &varsBat, const QString &varsBatArg,
+                                        ToolChain::Detection d = ToolChain::ManualDetection)
+{
+    ToolChain *tc = Utils::findOrDefault(alreadyKnown,
+                                         [&varsBat, &varsBatArg](ToolChain *tc) -> bool {
+                                              if (tc->typeId() != Constants::MSVC_TOOLCHAIN_TYPEID)
+                                                  return false;
+                                              auto mtc = static_cast<MsvcToolChain *>(tc);
+                                              return mtc->varsBat() == varsBat
+                                                      && mtc->varsBatArg() == varsBatArg;
+                                         });
+    if (!tc)
+        tc = new MsvcToolChain(name, abi, varsBat, varsBatArg, d);
+    return tc;
+}
+
 QList<ToolChain *> MsvcToolChainFactory::autoDetect(const QList<ToolChain *> &alreadyKnown)
 {
-    Q_UNUSED(alreadyKnown);
     QList<ToolChain *> results;
 
     // 1) Installed SDKs preferred over standalone Visual studio
@@ -550,16 +568,19 @@ QList<ToolChain *> MsvcToolChainFactory::autoDetect(const QList<ToolChain *> &al
                 continue;
 
             QList<ToolChain *> tmp;
-            tmp.append(new MsvcToolChain(generateDisplayName(name, MsvcToolChain::WindowsSDK, MsvcToolChain::x86),
-                                         findAbiOfMsvc(MsvcToolChain::WindowsSDK, MsvcToolChain::x86, sdkKey),
-                                         fi.absoluteFilePath(), QLatin1String("/x86"), ToolChain::AutoDetection));
+            tmp.append(findOrCreateToolChain(alreadyKnown,
+                                             generateDisplayName(name, MsvcToolChain::WindowsSDK, MsvcToolChain::x86),
+                                             findAbiOfMsvc(MsvcToolChain::WindowsSDK, MsvcToolChain::x86, sdkKey),
+                                             fi.absoluteFilePath(), QLatin1String("/x86"), ToolChain::AutoDetection));
             // Add all platforms, cross-compiler is automatically selected by SetEnv.cmd if needed
-            tmp.append(new MsvcToolChain(generateDisplayName(name, MsvcToolChain::WindowsSDK, MsvcToolChain::amd64),
-                                         findAbiOfMsvc(MsvcToolChain::WindowsSDK, MsvcToolChain::amd64, sdkKey),
-                                         fi.absoluteFilePath(), QLatin1String("/x64"), ToolChain::AutoDetection));
-            tmp.append(new MsvcToolChain(generateDisplayName(name, MsvcToolChain::WindowsSDK, MsvcToolChain::ia64),
-                                         findAbiOfMsvc(MsvcToolChain::WindowsSDK, MsvcToolChain::ia64, sdkKey),
-                                         fi.absoluteFilePath(), QLatin1String("/ia64"), ToolChain::AutoDetection));
+            tmp.append(findOrCreateToolChain(alreadyKnown,
+                                             generateDisplayName(name, MsvcToolChain::WindowsSDK, MsvcToolChain::amd64),
+                                             findAbiOfMsvc(MsvcToolChain::WindowsSDK, MsvcToolChain::amd64, sdkKey),
+                                             fi.absoluteFilePath(), QLatin1String("/x64"), ToolChain::AutoDetection));
+            tmp.append(findOrCreateToolChain(alreadyKnown,
+                                             generateDisplayName(name, MsvcToolChain::WindowsSDK, MsvcToolChain::ia64),
+                                             findAbiOfMsvc(MsvcToolChain::WindowsSDK, MsvcToolChain::ia64, sdkKey),
+                                             fi.absoluteFilePath(), QLatin1String("/ia64"), ToolChain::AutoDetection));
             // Make sure the default is front.
             if (folder == defaultSdkPath)
                 results = tmp + results;
@@ -601,11 +622,11 @@ QList<ToolChain *> MsvcToolChainFactory::autoDetect(const QList<ToolChain *> &al
             foreach (const MsvcToolChain::Platform &platform, platforms) {
                 if (hostSupportsPlatform(platform)
                         && QFileInfo(vcVarsBatFor(path, platform)).isFile()) {
-                    results.append(new MsvcToolChain(
+                    results.append(findOrCreateToolChain(
+                                       alreadyKnown,
                                        generateDisplayName(vsName, MsvcToolChain::VS, platform),
                                        findAbiOfMsvc(MsvcToolChain::VS, platform, vsName),
-                                       vcvarsAllbat,
-                                       platformName(platform),
+                                       vcvarsAllbat, platformName(platform),
                                        ToolChain::AutoDetection));
                 }
             }
diff --git a/src/plugins/projectexplorer/toolchainmanager.cpp b/src/plugins/projectexplorer/toolchainmanager.cpp
index afcf7567b8f..b26d0ceaa76 100644
--- a/src/plugins/projectexplorer/toolchainmanager.cpp
+++ b/src/plugins/projectexplorer/toolchainmanager.cpp
@@ -50,7 +50,6 @@ static const char TOOLCHAIN_DATA_KEY[] = "ToolChain.";
 static const char TOOLCHAIN_COUNT_KEY[] = "ToolChain.Count";
 static const char TOOLCHAIN_FILE_VERSION_KEY[] = "Version";
 static const char TOOLCHAIN_FILENAME[] = "/qtcreator/toolchains.xml";
-static const char LEGACY_TOOLCHAIN_FILENAME[] = "/toolChains.xml";
 
 using namespace Utils;
 
@@ -167,98 +166,146 @@ static QList<ToolChain *> restoreFromFile(const FileName &fileName)
     return result;
 }
 
+static QList<ToolChain *> autoDetectToolChains(const QList<ToolChain *> alreadyKnownTcs)
+{
+    QList<ToolChain *> result;
+    const QList<ToolChainFactory *> factories
+            = ExtensionSystem::PluginManager::getObjects<ToolChainFactory>();
+    foreach (ToolChainFactory *f, factories)
+        result.append(f->autoDetect(alreadyKnownTcs));
+
+    return result;
+}
+
+static QList<ToolChain *> subtractByEqual(const QList<ToolChain *> &a, const QList<ToolChain *> &b)
+{
+    return Utils::filtered(a, [&b](ToolChain *atc) {
+                                  return !Utils::anyOf(b, [atc](ToolChain *btc) { return *atc == *btc; });
+                              });
+}
+
+static QList<ToolChain *> subtractByPointerEqual(const QList<ToolChain *> &a, const QList<ToolChain *> &b)
+{
+    return Utils::filtered(a, [&b](ToolChain *atc) { return !b.contains(atc); });
+}
+
+static QList<ToolChain *> subtractById(const QList<ToolChain *> &a, const QList<ToolChain *> &b)
+{
+    return Utils::filtered(a, [&b](ToolChain *atc) {
+                                  return !Utils::anyOf(b, Utils::equal(&ToolChain::id, atc->id()));
+                              });
+}
+
+static QList<ToolChain *> intersectByEqual(const QList<ToolChain *> &a, const QList<ToolChain *> &b)
+{
+    return Utils::filtered(a, [&b](ToolChain *atc) {
+                                  return Utils::anyOf(b, [atc](ToolChain *btc) { return *atc == *btc; });
+                              });
+}
+
+static QList<ToolChain *> makeUnique(const QList<ToolChain *> &a)
+{
+    return QSet<ToolChain *>::fromList(a).toList();
+}
+
+namespace {
+
+struct ToolChainOperations
+{
+    QList<ToolChain *> toDemote;
+    QList<ToolChain *> toRegister;
+    QList<ToolChain *> toDelete;
+};
+
+} // namespace
+
+static ToolChainOperations mergeToolChainLists(const QList<ToolChain *> &systemFileTcs,
+                                               const QList<ToolChain *> &userFileTcs,
+                                               const QList<ToolChain *> &autodetectedTcs)
+{
+    const QList<ToolChain *> manualUserTcs
+            = Utils::filtered(userFileTcs, [](ToolChain *t) { return !t->isAutoDetected(); });
+
+    // Remove systemFileTcs from autodetectedUserTcs based on id-matches:
+    const QList<ToolChain *> autodetectedUserFileTcs
+            = Utils::filtered(userFileTcs, &ToolChain::isAutoDetected);
+    const QList<ToolChain *> autodetectedUserTcs = subtractById(autodetectedUserFileTcs, systemFileTcs);
+
+    // Calculate a set of Tcs that were detected before (and saved to userFile) and that
+    // got re-detected again. Take the userTcs (to keep Ids) over the same in autodetectedTcs.
+    const QList<ToolChain *> redetectedUserTcs
+            = intersectByEqual(autodetectedUserTcs, autodetectedTcs);
+
+    // Remove redetected tcs from autodetectedUserTcs:
+    const QList<ToolChain *> notRedetectedUserTcs
+            = subtractByPointerEqual(autodetectedUserTcs, redetectedUserTcs);
+
+    // Remove redetected tcs from autodetectedTcs:
+    const QList<ToolChain *> newlyAutodetectedTcs
+            = subtractByEqual(autodetectedTcs, redetectedUserTcs);
+
+    const QList<ToolChain *> notRedetectedButValidUserTcs
+            = Utils::filtered(notRedetectedUserTcs, &ToolChain::isValid);
+
+    const QList<ToolChain *> validManualUserTcs
+            = Utils::filtered(manualUserTcs, &ToolChain::isValid);
+
+    ToolChainOperations result;
+    result.toDemote = notRedetectedButValidUserTcs;
+    result.toRegister = result.toDemote + systemFileTcs + redetectedUserTcs + newlyAutodetectedTcs
+            + validManualUserTcs;
+
+    result.toDelete = makeUnique(subtractByPointerEqual(systemFileTcs + userFileTcs + autodetectedTcs,
+                                                        result.toRegister));
+    return result;
+}
+
 void ToolChainManager::restoreToolChains()
 {
     QTC_ASSERT(!d->m_writer, return);
     d->m_writer =
-            new PersistentSettingsWriter(settingsFileName(QLatin1String(TOOLCHAIN_FILENAME)), QLatin1String("QtCreatorToolChains"));
-
-    QList<ToolChain *> tcsToRegister;
-    QList<ToolChain *> tcsToCheck;
+            new PersistentSettingsWriter(settingsFileName(QLatin1String(TOOLCHAIN_FILENAME)),
+                                         QLatin1String("QtCreatorToolChains"));
 
     // read all tool chains from SDK
-    QFileInfo systemSettingsFile(Core::ICore::settings(QSettings::SystemScope)->fileName());
-    QList<ToolChain *> readTcs =
-            restoreFromFile(FileName::fromString(systemSettingsFile.absolutePath() + QLatin1String(TOOLCHAIN_FILENAME)));
-    // make sure we mark these as autodetected!
-    foreach (ToolChain *tc, readTcs)
-        tc->setDetection(ToolChain::AutoDetection);
-
-    tcsToRegister = readTcs; // SDK TCs are always considered to be up-to-date, so no need to
-                             // recheck them.
+    const QList<ToolChain *> systemFileTcs = readSystemFileToolChains();
 
     // read all tool chains from user file.
-    // Read legacy settings once and keep them around...
-    FileName fileName = settingsFileName(QLatin1String(TOOLCHAIN_FILENAME));
-    if (!fileName.exists())
-        fileName = settingsFileName(QLatin1String(LEGACY_TOOLCHAIN_FILENAME));
-    readTcs = restoreFromFile(fileName);
+    const QList<ToolChain *> userFileTcs
+            = restoreFromFile(settingsFileName(QLatin1String(TOOLCHAIN_FILENAME)));
 
-    foreach (ToolChain *tc, readTcs) {
-        if (tc->isAutoDetected())
-            tcsToCheck.append(tc);
-        else
-            tcsToRegister.append(tc);
-    }
-    readTcs.clear();
+    // Autodetect: Pass autodetected toolchains from user file so the information can be reused:
+    const QList<ToolChain *> autodetectedUserFileTcs
+            = Utils::filtered(userFileTcs, &ToolChain::isAutoDetected);
+    const QList<ToolChain *> autodetectedTcs = autoDetectToolChains(autodetectedUserFileTcs);
 
-    // Remove TCs configured by the SDK:
-    foreach (ToolChain *tc, tcsToRegister) {
-        for (int i = tcsToCheck.count() - 1; i >= 0; --i) {
-            if (tcsToCheck.at(i)->id() == tc->id()) {
-                delete tcsToCheck.at(i);
-                tcsToCheck.removeAt(i);
-            }
-        }
-    }
+    // merge tool chains and register those that we need to keep:
+    ToolChainOperations ops = mergeToolChainLists(systemFileTcs, userFileTcs, autodetectedTcs);
 
-    // Then auto detect
-    QList<ToolChain *> detectedTcs = tcsToCheck;
-    QList<ToolChainFactory *> factories = ExtensionSystem::PluginManager::getObjects<ToolChainFactory>();
-    foreach (ToolChainFactory *f, factories)
-        detectedTcs.append(f->autoDetect(tcsToCheck));
+    // Process ops:
+    foreach (ToolChain *tc, ops.toDemote)
+        tc->setDetection(ToolChain::ManualDetection);
 
-    // Find/update autodetected tool chains:
-    ToolChain *toStore = 0;
-    foreach (ToolChain *currentDetected, detectedTcs) {
-        toStore = currentDetected;
-
-        // Check whether we had this TC stored and prefer the old one with the old id, marked
-        // as auto-detection.
-        for (int i = 0; i < tcsToCheck.count(); ++i) {
-            if (tcsToCheck.at(i) == currentDetected) {
-                tcsToCheck.removeAt(i);
-                break;
-            } else if (*(tcsToCheck.at(i)) == *currentDetected) {
-                toStore = tcsToCheck.at(i);
-                toStore->setDetection(ToolChain::AutoDetection);
-                tcsToCheck.removeAt(i);
-                delete currentDetected;
-                break;
-            }
-        }
-        tcsToRegister += toStore;
-    }
-
-    // Keep toolchains that were not rediscovered but are still executable and delete the rest
-    foreach (ToolChain *tc, tcsToCheck) {
-        if (!tc->isValid()) {
-            qWarning() << QString::fromLatin1("ToolChain \"%1\" (%2) dropped since it is not valid")
-                          .arg(tc->displayName()).arg(QString::fromUtf8(tc->id()));
-            delete tc;
-        } else {
-            tc->setDetection(ToolChain::ManualDetection); // "demote" to manual toolchain
-            tcsToRegister += tc;
-        }
-    }
-
-    // Store manual tool chains
-    foreach (ToolChain *tc, tcsToRegister)
+    foreach (ToolChain *tc, ops.toRegister)
         registerToolChain(tc);
 
+    qDeleteAll(ops.toDelete);
+
     emit m_instance->toolChainsLoaded();
 }
 
+QList<ToolChain *> ToolChainManager::readSystemFileToolChains()
+{
+    QFileInfo systemSettingsFile(Core::ICore::settings(QSettings::SystemScope)->fileName());
+    QList<ToolChain *> systemTcs
+            = restoreFromFile(FileName::fromString(systemSettingsFile.absolutePath() + QLatin1String(TOOLCHAIN_FILENAME)));
+
+    foreach (ToolChain *tc, systemTcs)
+        tc->setDetection(ToolChain::AutoDetection);
+
+    return systemTcs;
+}
+
 void ToolChainManager::saveToolChains()
 {
     QVariantMap data;
diff --git a/src/plugins/projectexplorer/toolchainmanager.h b/src/plugins/projectexplorer/toolchainmanager.h
index f787272a350..9214ac30109 100644
--- a/src/plugins/projectexplorer/toolchainmanager.h
+++ b/src/plugins/projectexplorer/toolchainmanager.h
@@ -87,6 +87,9 @@ private:
     // Make sure the this is only called after all
     // Tool chain Factories are registered!
     static void restoreToolChains();
+
+    static QList<ToolChain *> readSystemFileToolChains();
+
     static void notifyAboutUpdate(ToolChain *);
 
     friend class ProjectExplorerPlugin; // for constructor
diff --git a/src/plugins/projectexplorer/wincetoolchain.cpp b/src/plugins/projectexplorer/wincetoolchain.cpp
index e83e75947c7..5b6a73301fc 100644
--- a/src/plugins/projectexplorer/wincetoolchain.cpp
+++ b/src/plugins/projectexplorer/wincetoolchain.cpp
@@ -33,6 +33,7 @@
 #include "msvcparser.h"
 #include "projectexplorerconstants.h"
 
+#include <utils/algorithm.h>
 #include <utils/qtcassert.h>
 
 #include <QDir>
@@ -352,10 +353,33 @@ WinCEToolChainFactory::WinCEToolChainFactory()
     setDisplayName(tr("WinCE"));
 }
 
+static ToolChain *findOrCreateToolChain(const QList<ToolChain *> &alreadyKnown,
+                                        const QString &name, const Abi &abi,
+                                        const QString &vcvarsBat, const QString &msvcVer,
+                                        const QString &ceVer, const QString &binPath,
+                                        const QString &includePath, const QString &libPath,
+                                        ToolChain::Detection d = ToolChain::ManualDetection)
+{
+    ToolChain *tc
+            = Utils::findOrDefault(alreadyKnown, [&](ToolChain *tc) -> bool {
+                                       if (tc->typeId() != Constants::WINCE_TOOLCHAIN_TYPEID)
+                                           return false;
+                                       auto cetc = static_cast<WinCEToolChain *>(tc);
+                                       return cetc->targetAbi() == abi
+                                                  && cetc->varsBat() == vcvarsBat
+                                                  && cetc->msvcVer() == msvcVer
+                                                  && cetc->ceVer() == ceVer
+                                                  && cetc->binPath() == binPath
+                                                  && cetc->includePath() == includePath
+                                                  && cetc->libPath() == libPath;
+                                         });
+    if (!tc)
+        tc = new WinCEToolChain(name, abi, vcvarsBat, msvcVer, ceVer, binPath, includePath, libPath, d);
+    return tc;
+}
 
 QList<ToolChain *> WinCEToolChainFactory::autoDetect(const QList<ToolChain *> &alreadyKnown)
 {
-    Q_UNUSED(alreadyKnown);
     QList<ToolChain *> results;
 
     // 1) Installed WinCEs
@@ -398,16 +422,16 @@ QList<ToolChain *> WinCEToolChainFactory::autoDetect(const QList<ToolChain *> &a
                         QString ceVer;
 
                         if (parseSDK(platformReader, theArch, thePlat, ceVer, binPath, includePath, libPath)) {
-                            WinCEToolChain *pChain = new WinCEToolChain(thePlat,
-                                                                        Abi(theArch, Abi::WindowsOS, Abi::WindowsCEFlavor, Abi::PEFormat, 32),
-                                                                        vcvars32bat,
-                                                                        msvcVer,
-                                                                        ceVer,
-                                                                        binPath,
-                                                                        includePath,
-                                                                        libPath,
-                                                                        ToolChain::AutoDetection);
-                            results.append(pChain);
+                            results.append(findOrCreateToolChain(alreadyKnown,
+                                                                 thePlat,
+                                                                 Abi(theArch, Abi::WindowsOS, Abi::WindowsCEFlavor, Abi::PEFormat, 32),
+                                                                 vcvars32bat,
+                                                                 msvcVer,
+                                                                 ceVer,
+                                                                 binPath,
+                                                                 includePath,
+                                                                 libPath,
+                                                                 ToolChain::AutoDetection));
                         }
                     }
                 }
diff --git a/src/plugins/projectexplorer/wincetoolchain.h b/src/plugins/projectexplorer/wincetoolchain.h
index 221d4ced45f..44c0e3f3c68 100644
--- a/src/plugins/projectexplorer/wincetoolchain.h
+++ b/src/plugins/projectexplorer/wincetoolchain.h
@@ -57,8 +57,13 @@ public:
 
     QString typeDisplayName() const override;
 
+    QString msvcVer() const { return m_msvcVer; }
     QString ceVer() const;
 
+    QString binPath() const { return m_binPath; }
+    QString includePath() const { return m_includePath; }
+    QString libPath() const { return m_libPath; }
+
     QVariantMap toMap() const override;
     bool fromMap(const QVariantMap &data) override;