diff --git a/src/plugins/baremetal/iarewtoolchain.cpp b/src/plugins/baremetal/iarewtoolchain.cpp
index 5e3f81f85b5..dda9e47e00c 100644
--- a/src/plugins/baremetal/iarewtoolchain.cpp
+++ b/src/plugins/baremetal/iarewtoolchain.cpp
@@ -309,7 +309,7 @@ public:
     void addToEnvironment(Environment &env) const final;
     QList<OutputLineParser *> createOutputParsers() const final;
 
-    QVariantMap toMap() const final;
+    void toMap(QVariantMap &data) const final;
     bool fromMap(const QVariantMap &data) final;
 
     std::unique_ptr<ToolChainConfigWidget> createConfigurationWidget() final;
@@ -404,11 +404,10 @@ QList<Utils::OutputLineParser *> IarToolChain::createOutputParsers() const
     return {new IarParser()};
 }
 
-QVariantMap IarToolChain::toMap() const
+void IarToolChain::toMap(QVariantMap &data) const
 {
-    QVariantMap data = ToolChain::toMap();
+    ToolChain::toMap(data);
     data.insert(compilerPlatformCodeGenFlagsKeyC, m_extraCodeModelFlags);
-    return data;
 }
 
 bool IarToolChain::fromMap(const QVariantMap &data)
diff --git a/src/plugins/baremetal/keiltoolchain.cpp b/src/plugins/baremetal/keiltoolchain.cpp
index 3da4c04248a..9257a8d781c 100644
--- a/src/plugins/baremetal/keiltoolchain.cpp
+++ b/src/plugins/baremetal/keiltoolchain.cpp
@@ -449,7 +449,7 @@ public:
 
     QList<OutputLineParser *> createOutputParsers() const final { return {new KeilParser}; }
 
-    QVariantMap toMap() const final;
+    void toMap(QVariantMap &data) const final;
     bool fromMap(const QVariantMap &data) final;
 
     std::unique_ptr<ToolChainConfigWidget> createConfigurationWidget() final;
@@ -527,11 +527,10 @@ void KeilToolChain::addToEnvironment(Environment &env) const
 }
 
 
-QVariantMap KeilToolChain::toMap() const
+void KeilToolChain::toMap(QVariantMap &data) const
 {
-    QVariantMap data = ToolChain::toMap();
+    ToolChain::toMap(data);
     data.insert(compilerPlatformCodeGenFlagsKeyC, m_extraCodeModelFlags);
-    return data;
 }
 
 bool KeilToolChain::fromMap(const QVariantMap &data)
diff --git a/src/plugins/projectexplorer/customtoolchain.cpp b/src/plugins/projectexplorer/customtoolchain.cpp
index 9c7ab0a4088..c15ade15c08 100644
--- a/src/plugins/projectexplorer/customtoolchain.cpp
+++ b/src/plugins/projectexplorer/customtoolchain.cpp
@@ -217,9 +217,9 @@ QString CustomToolChain::mkspecs() const
     return m_mkspecs.join(',');
 }
 
-QVariantMap CustomToolChain::toMap() const
+void CustomToolChain::toMap(QVariantMap &data) const
 {
-    QVariantMap data = ToolChain::toMap();
+    ToolChain::toMap(data);
     data.insert(QLatin1String(makeCommandKeyC), m_makeCommand.toString());
     QStringList macros = Utils::transform<QList>(m_predefinedMacros, [](const Macro &m) { return QString::fromUtf8(m.toByteArray()); });
     data.insert(QLatin1String(predefinedMacrosKeyC), macros);
@@ -227,8 +227,6 @@ QVariantMap CustomToolChain::toMap() const
     data.insert(QLatin1String(cxx11FlagsKeyC), m_cxx11Flags);
     data.insert(QLatin1String(mkspecsKeyC), mkspecs());
     data.insert(QLatin1String(outputParserKeyC), m_outputParserId.toSetting());
-
-    return data;
 }
 
 bool CustomToolChain::fromMap(const QVariantMap &data)
diff --git a/src/plugins/projectexplorer/customtoolchain.h b/src/plugins/projectexplorer/customtoolchain.h
index 3da4dfd9160..b01850a43cd 100644
--- a/src/plugins/projectexplorer/customtoolchain.h
+++ b/src/plugins/projectexplorer/customtoolchain.h
@@ -56,7 +56,7 @@ public:
     QStringList headerPathsList() const;
     void setHeaderPaths(const QStringList &list);
 
-    QVariantMap toMap() const override;
+    void toMap(QVariantMap &data) const override;
     bool fromMap(const QVariantMap &data) override;
 
     std::unique_ptr<ToolChainConfigWidget> createConfigurationWidget() override;
diff --git a/src/plugins/projectexplorer/gcctoolchain.cpp b/src/plugins/projectexplorer/gcctoolchain.cpp
index f69ab0afc8f..c6f74d565b3 100644
--- a/src/plugins/projectexplorer/gcctoolchain.cpp
+++ b/src/plugins/projectexplorer/gcctoolchain.cpp
@@ -795,14 +795,13 @@ QStringList GccToolChain::platformLinkerFlags() const
     return m_platformLinkerFlags;
 }
 
-QVariantMap GccToolChain::toMap() const
+void GccToolChain::toMap(QVariantMap &data) const
 {
-    QVariantMap data = ToolChain::toMap();
+    ToolChain::toMap(data);
     data.insert(compilerPlatformCodeGenFlagsKeyC, m_platformCodeGenFlags);
     data.insert(compilerPlatformLinkerFlagsKeyC, m_platformLinkerFlags);
     data.insert(originalTargetTripleKeyC, m_originalTargetTriple);
     data.insert(supportedAbisKeyC, Utils::transform<QStringList>(m_supportedAbis, &Abi::toString));
-    return data;
 }
 
 bool GccToolChain::fromMap(const QVariantMap &data)
@@ -1713,12 +1712,11 @@ std::unique_ptr<ToolChainConfigWidget> ClangToolChain::createConfigurationWidget
     return std::make_unique<ClangToolChainConfigWidget>(this);
 }
 
-QVariantMap ClangToolChain::toMap() const
+void ClangToolChain::toMap(QVariantMap &data) const
 {
-    QVariantMap data = GccToolChain::toMap();
+    GccToolChain::toMap(data);
     data.insert(parentToolChainIdKeyC, m_parentToolChainId);
     data.insert(priorityKeyC, m_priority);
-    return data;
 }
 
 bool ClangToolChain::fromMap(const QVariantMap &data)
diff --git a/src/plugins/projectexplorer/gcctoolchain.h b/src/plugins/projectexplorer/gcctoolchain.h
index 1e6353d0a75..96ab49df3d2 100644
--- a/src/plugins/projectexplorer/gcctoolchain.h
+++ b/src/plugins/projectexplorer/gcctoolchain.h
@@ -66,7 +66,7 @@ public:
     QStringList suggestedMkspecList() const override;
     QList<Utils::OutputLineParser *> createOutputParsers() const override;
 
-    QVariantMap toMap() const override;
+    void toMap(QVariantMap &data) const override;
     bool fromMap(const QVariantMap &data) override;
 
     std::unique_ptr<ToolChainConfigWidget> createConfigurationWidget() override;
@@ -206,7 +206,7 @@ public:
 
     std::unique_ptr<ToolChainConfigWidget> createConfigurationWidget() override;
 
-    QVariantMap toMap() const override;
+    void toMap(QVariantMap &data) const override;
     bool fromMap(const QVariantMap &data) override;
 
     void setPriority(int priority) { m_priority = priority; }
diff --git a/src/plugins/projectexplorer/msvctoolchain.cpp b/src/plugins/projectexplorer/msvctoolchain.cpp
index d4d518de44d..095978bb91d 100644
--- a/src/plugins/projectexplorer/msvctoolchain.cpp
+++ b/src/plugins/projectexplorer/msvctoolchain.cpp
@@ -978,16 +978,15 @@ Abis MsvcToolChain::supportedAbis() const
     return abis;
 }
 
-QVariantMap MsvcToolChain::toMap() const
+void MsvcToolChain::toMap(QVariantMap &data) const
 {
-    QVariantMap data = ToolChain::toMap();
+    ToolChain::toMap(data);
     data.insert(QLatin1String(varsBatKeyC), m_vcvarsBat);
     if (!m_varsBatArg.isEmpty())
         data.insert(QLatin1String(varsBatArgKeyC), m_varsBatArg);
     Utils::EnvironmentItem::sort(&m_environmentModifications);
     data.insert(QLatin1String(environModsKeyC),
                 Utils::EnvironmentItem::toVariantList(m_environmentModifications));
-    return data;
 }
 
 bool MsvcToolChain::fromMap(const QVariantMap &data)
@@ -1728,11 +1727,10 @@ static inline QString llvmDirKey()
     return QStringLiteral("ProjectExplorer.ClangClToolChain.LlvmDir");
 }
 
-QVariantMap ClangClToolChain::toMap() const
+void ClangClToolChain::toMap(QVariantMap &data) const
 {
-    QVariantMap result = MsvcToolChain::toMap();
-    result.insert(llvmDirKey(), m_clangPath.toString());
-    return result;
+    MsvcToolChain::toMap(data);
+    data.insert(llvmDirKey(), m_clangPath.toString());
 }
 
 bool ClangClToolChain::fromMap(const QVariantMap &data)
diff --git a/src/plugins/projectexplorer/msvctoolchain.h b/src/plugins/projectexplorer/msvctoolchain.h
index 68f8b9dcf19..77cd18a647a 100644
--- a/src/plugins/projectexplorer/msvctoolchain.h
+++ b/src/plugins/projectexplorer/msvctoolchain.h
@@ -46,7 +46,7 @@ public:
     QStringList suggestedMkspecList() const override;
     Abis supportedAbis() const override;
 
-    QVariantMap toMap() const override;
+    void toMap(QVariantMap &data) const override;
     bool fromMap(const QVariantMap &data) override;
 
     std::unique_ptr<ToolChainConfigWidget> createConfigurationWidget() override;
@@ -146,7 +146,7 @@ public:
     void addToEnvironment(Utils::Environment &env) const override;
     Utils::FilePath compilerCommand() const override; // FIXME: Remove
     QList<Utils::OutputLineParser *> createOutputParsers() const override;
-    QVariantMap toMap() const override;
+    void toMap(QVariantMap &data) const override;
     bool fromMap(const QVariantMap &data) override;
     std::unique_ptr<ToolChainConfigWidget> createConfigurationWidget() override;
     BuiltInHeaderPathsRunner createBuiltInHeaderPathsRunner(
diff --git a/src/plugins/projectexplorer/toolchain.cpp b/src/plugins/projectexplorer/toolchain.cpp
index f1a8f80c22d..4373114a028 100644
--- a/src/plugins/projectexplorer/toolchain.cpp
+++ b/src/plugins/projectexplorer/toolchain.cpp
@@ -226,7 +226,9 @@ ToolChain *ToolChain::clone() const
         if (f->supportedToolChainType() == d->m_typeId) {
             ToolChain *tc = f->create();
             QTC_ASSERT(tc, return nullptr);
-            tc->fromMap(toMap());
+            QVariantMap data;
+            toMap(data);
+            tc->fromMap(data);
             // New ID for the clone. It's different.
             tc->d->m_id = QUuid::createUuid().toByteArray();
             return tc;
@@ -242,9 +244,8 @@ ToolChain *ToolChain::clone() const
     Make sure to call this function when deriving.
 */
 
-QVariantMap ToolChain::toMap() const
+void ToolChain::toMap(QVariantMap &result) const
 {
-    QVariantMap result;
     QString idToSave = d->m_typeId.toString() + QLatin1Char(':') + QString::fromUtf8(id());
     result.insert(QLatin1String(ID_KEY), idToSave);
     result.insert(QLatin1String(DISPLAY_NAME_KEY), displayName());
@@ -265,7 +266,6 @@ QVariantMap ToolChain::toMap() const
         result.insert(d->m_targetAbiKey, d->m_targetAbi.toString());
     if (!d->m_compilerCommandKey.isEmpty())
         result.insert(d->m_compilerCommandKey, d->m_compilerCommand.toSettings());
-    return result;
 }
 
 void ToolChain::toolChainUpdated()
diff --git a/src/plugins/projectexplorer/toolchain.h b/src/plugins/projectexplorer/toolchain.h
index 35cad5333ee..f1a0894ef31 100644
--- a/src/plugins/projectexplorer/toolchain.h
+++ b/src/plugins/projectexplorer/toolchain.h
@@ -145,7 +145,7 @@ public:
 
     // Used by the toolchainmanager to save user-generated tool chains.
     // Make sure to call this function when deriving!
-    virtual QVariantMap toMap() const;
+    virtual void toMap(QVariantMap &map) const;
     virtual Tasks validateKit(const Kit *k) const;
 
     virtual bool isJobCountSupported() const { return true; }
diff --git a/src/plugins/projectexplorer/toolchainsettingsaccessor.cpp b/src/plugins/projectexplorer/toolchainsettingsaccessor.cpp
index 9354f6e62db..a001f509496 100644
--- a/src/plugins/projectexplorer/toolchainsettingsaccessor.cpp
+++ b/src/plugins/projectexplorer/toolchainsettingsaccessor.cpp
@@ -220,7 +220,8 @@ void ToolChainSettingsAccessor::saveToolChains(const Toolchains &toolchains, QWi
     for (const ToolChain *tc : toolchains) {
         if (!tc || (!tc->isValid() && tc->isAutoDetected()))
             continue;
-        const QVariantMap tmp = tc->toMap();
+        QVariantMap tmp;
+        tc->toMap(tmp);
         if (tmp.isEmpty())
             continue;
         data.insert(QString::fromLatin1(TOOLCHAIN_DATA_KEY) + QString::number(count), tmp);
@@ -326,11 +327,10 @@ public:
         return true;
     }
 
-    QVariantMap toMap() const final
+    void toMap(QVariantMap &data) const final
     {
-        QVariantMap data = ToolChain::toMap();
+        ToolChain::toMap(data);
         data[TestTokenKey] = token;
-        return data;
     }
 
     QByteArray token;
@@ -339,8 +339,6 @@ private:
     bool m_valid = false;
 
     static QList<TTC *> m_toolChains;
-
-public:
 };
 
 QList<TTC *> TTC::m_toolChains;
diff --git a/src/plugins/qnx/qnxtoolchain.cpp b/src/plugins/qnx/qnxtoolchain.cpp
index 8176b3d17c9..0d8f9a01095 100644
--- a/src/plugins/qnx/qnxtoolchain.cpp
+++ b/src/plugins/qnx/qnxtoolchain.cpp
@@ -131,12 +131,11 @@ QStringList QnxToolChain::suggestedMkspecList() const
     };
 }
 
-QVariantMap QnxToolChain::toMap() const
+void QnxToolChain::toMap(QVariantMap &data) const
 {
-    QVariantMap data = GccToolChain::toMap();
+    GccToolChain::toMap(data);
     data.insert(QLatin1String(CompilerSdpPath), m_sdpPath.toSettings());
     data.insert(QLatin1String(CpuDirKey), m_cpuDir);
-    return data;
 }
 
 bool QnxToolChain::fromMap(const QVariantMap &data)
diff --git a/src/plugins/qnx/qnxtoolchain.h b/src/plugins/qnx/qnxtoolchain.h
index e2edb76f8ee..c38249d8546 100644
--- a/src/plugins/qnx/qnxtoolchain.h
+++ b/src/plugins/qnx/qnxtoolchain.h
@@ -21,7 +21,7 @@ public:
     void addToEnvironment(Utils::Environment &env) const override;
     QStringList suggestedMkspecList() const override;
 
-    QVariantMap toMap() const override;
+    void toMap(QVariantMap &data) const override;
     bool fromMap(const QVariantMap &data) override;
 
     Utils::FilePath sdpPath() const;