diff --git a/src/Magnum/ShaderTools/AbstractConverter.cpp b/src/Magnum/ShaderTools/AbstractConverter.cpp
index 8e70275d0..fd063cfa2 100644
--- a/src/Magnum/ShaderTools/AbstractConverter.cpp
+++ b/src/Magnum/ShaderTools/AbstractConverter.cpp
@@ -79,13 +79,16 @@ AbstractConverter::AbstractConverter(PluginManager::AbstractManager& manager, co
 
 ConverterFeatures AbstractConverter::features() const {
     const ConverterFeatures features = doFeatures();
-    CORRADE_ASSERT(features & ~ConverterFeature::InputFileCallback, "ShaderTools::AbstractConverter::features(): implementation reported no features", {});
+    CORRADE_ASSERT(features & ~(ConverterFeature::InputFileCallback|ConverterFeature::Preprocess),
+        "ShaderTools::AbstractConverter::features(): implementation reported no features", {});
     return features;
 }
 
 void AbstractConverter::setFlags(const ConverterFlags flags) {
-    CORRADE_ASSERT(!(flags & ConverterFlag::Quiet) != !(flags & ConverterFlag::Verbose),
-        "ShaderTools::AbstractConverter::setFeatures(): can't have both Quiet and Verbose set", );
+    CORRADE_ASSERT(!(flags >= (ConverterFlag::Quiet|ConverterFlag::Verbose)),
+        "ShaderTools::AbstractConverter::setFlags(): can't have both Quiet and Verbose set", );
+    CORRADE_ASSERT((features() & ConverterFeature::Preprocess) || !(flags & ConverterFlag::PreprocessOnly),
+        "ShaderTools::AbstractConverter::setFlags(): PreprocessOnly not supported by the implementation", );
     _flags = flags;
     doSetFlags(flags);
 }
@@ -122,6 +125,20 @@ void AbstractConverter::setOutputFormat(const Format format) {
     return setOutputFormat(format, {});
 }
 
+void AbstractConverter::setDefinitions(const Containers::ArrayView<const std::pair<Containers::StringView, Containers::StringView>> definitions) {
+    CORRADE_ASSERT(features() & ConverterFeature::Preprocess,
+        "ShaderTools::AbstractConverter::setDefinitions(): feature not supported", );
+    doSetDefinitions(definitions);
+}
+
+void AbstractConverter::setDefinitions(std::initializer_list<std::pair<Containers::StringView, Containers::StringView>> definitions) {
+    return setDefinitions(Containers::arrayView(definitions));
+}
+
+void AbstractConverter::doSetDefinitions(Containers::ArrayView<const std::pair<Containers::StringView, Containers::StringView>>) {
+    CORRADE_ASSERT_UNREACHABLE("ShaderTools::AbstractConverter::setDefinitions(): feature advertised but not implemented", );
+}
+
 std::pair<bool, Containers::String> AbstractConverter::validateData(const Stage stage, const Containers::ArrayView<const void> data) {
     CORRADE_ASSERT(features() & ConverterFeature::ValidateData,
         "ShaderTools::AbstractConverter::validateData(): feature not supported", {});
@@ -371,6 +388,8 @@ Containers::Array<char> AbstractConverter::doConvertFileToData(const Stage stage
 Containers::Array<char> AbstractConverter::linkDataToData(const Containers::ArrayView<const std::pair<Stage, Containers::ArrayView<const void>>> data) {
     CORRADE_ASSERT(features() >= ConverterFeature::LinkData,
         "ShaderTools::AbstractConverter::linkDataToData(): feature not supported", {});
+    CORRADE_ASSERT(!(_flags & ConverterFlag::PreprocessOnly),
+        "ShaderTools::AbstractConverter::linkDataToData(): PreprocessOnly is not allowed in combination with linking", {});
     CORRADE_ASSERT(!data.empty(),
         "ShaderTools::AbstractConverter::linkDataToData(): no data passed", {});
 
@@ -392,6 +411,8 @@ Containers::Array<char> AbstractConverter::doLinkDataToData(Containers::ArrayVie
 bool AbstractConverter::linkDataToFile(const Containers::ArrayView<const std::pair<Stage, Containers::ArrayView<const void>>> data, const Containers::StringView to) {
     CORRADE_ASSERT(features() >= ConverterFeature::LinkData,
         "ShaderTools::AbstractConverter::linkDataToFile(): feature not supported", {});
+    CORRADE_ASSERT(!(_flags & ConverterFlag::PreprocessOnly),
+        "ShaderTools::AbstractConverter::linkDataToFile(): PreprocessOnly is not allowed in combination with linking", {});
     CORRADE_ASSERT(!data.empty(),
         "ShaderTools::AbstractConverter::linkDataToFile(): no data passed", {});
 
@@ -451,6 +472,8 @@ Containers::Array<char> AbstractConverter::linkDataToDataUsingInputFileCallbacks
 bool AbstractConverter::linkFilesToFile(const Containers::ArrayView<const std::pair<Stage, Containers::StringView>> from, const Containers::StringView to) {
     CORRADE_ASSERT(features() & (ConverterFeature::LinkFile|ConverterFeature::LinkData),
         "ShaderTools::AbstractConverter::linkFilesToFile(): feature not supported", {});
+    CORRADE_ASSERT(!(_flags & ConverterFlag::PreprocessOnly),
+        "ShaderTools::AbstractConverter::linkFilesToFile(): PreprocessOnly is not allowed in combination with linking", {});
     CORRADE_ASSERT(!from.empty(),
         "ShaderTools::AbstractConverter::linkFilesToFile(): no files passed", {});
 
@@ -539,6 +562,8 @@ bool AbstractConverter::doLinkFilesToFile(const Containers::ArrayView<const std:
 Containers::Array<char> AbstractConverter::linkFilesToData(const Containers::ArrayView<const std::pair<Stage, Containers::StringView>> from) {
     CORRADE_ASSERT(features() >= ConverterFeature::LinkData,
         "ShaderTools::AbstractConverter::linkFilesToData(): feature not supported", {});
+    CORRADE_ASSERT(!(_flags & ConverterFlag::PreprocessOnly),
+        "ShaderTools::AbstractConverter::linkFilesToData(): PreprocessOnly is not allowed in combination with linking", {});
     CORRADE_ASSERT(!from.empty(),
         "ShaderTools::AbstractConverter::linkFilesToData(): no files passed", {});
 
@@ -617,6 +642,7 @@ Debug& operator<<(Debug& debug, const ConverterFeature value) {
         _c(LinkData)
         _c(LinkFile)
         _c(InputFileCallback)
+        _c(Preprocess)
         #undef _c
         /* LCOV_EXCL_STOP */
     }
@@ -635,7 +661,9 @@ Debug& operator<<(Debug& debug, const ConverterFeatures value) {
         ConverterFeature::LinkData,
         /* Implied by LinkData, has to be after */
         ConverterFeature::LinkFile,
-        ConverterFeature::InputFileCallback});
+        ConverterFeature::InputFileCallback,
+        ConverterFeature::Preprocess
+    });
 }
 
 Debug& operator<<(Debug& debug, const ConverterFlag value) {
@@ -647,6 +675,7 @@ Debug& operator<<(Debug& debug, const ConverterFlag value) {
         _c(Quiet)
         _c(Verbose)
         _c(WarningAsError)
+        _c(PreprocessOnly)
         #undef _c
         /* LCOV_EXCL_STOP */
     }
@@ -658,7 +687,8 @@ Debug& operator<<(Debug& debug, const ConverterFlags value) {
     return Containers::enumSetDebugOutput(debug, value, "ShaderTools::ConverterFlags{}", {
         ConverterFlag::Quiet,
         ConverterFlag::Verbose,
-        ConverterFlag::WarningAsError
+        ConverterFlag::WarningAsError,
+        ConverterFlag::PreprocessOnly
     });
 }
 
diff --git a/src/Magnum/ShaderTools/AbstractConverter.h b/src/Magnum/ShaderTools/AbstractConverter.h
index 85abd2109..002d5dd04 100644
--- a/src/Magnum/ShaderTools/AbstractConverter.h
+++ b/src/Magnum/ShaderTools/AbstractConverter.h
@@ -94,7 +94,13 @@ enum class ConverterFeature: UnsignedInt {
      * See @ref ShaderTools-AbstractConverter-usage-callbacks and particular
      * converter documentation for more information.
      */
-    InputFileCallback = 1 << 6
+    InputFileCallback = 1 << 6,
+
+    /**
+     * Set preprocess definitions using @ref AbstractConverter::setDefinitions()
+     * and the @ref ConverterFlag::PreprocessOnly flag.
+     */
+    Preprocess = 1 << 7
 };
 
 /**
@@ -144,7 +150,17 @@ enum class ConverterFlag: UnsignedInt {
      * validation or conversion succeeds. With this flag set, it fails.
      * @see @ref ConverterFlag::Quiet
      */
-    WarningAsError = 1 << 2
+    WarningAsError = 1 << 2,
+
+    /**
+     * Only run the preprocessor. Available only if the converter supports
+     * @ref ConverterFeature::Preprocess, not allowed in combination with
+     * @ref AbstractConverter::linkDataToData(),
+     * @ref AbstractConverter::linkDataToFile(),
+     * @ref AbstractConverter::linkFilesToFile() or
+     * @ref AbstractConverter::linkFilesToData().
+     */
+    PreprocessOnly = 1 << 3
 };
 
 /**
@@ -574,6 +590,24 @@ class MAGNUM_SHADERTOOLS_EXPORT AbstractConverter: public PluginManager::Abstrac
         void setOutputFormat(Format format);
         #endif
 
+        /**
+         * @brief Set preprocessor definitions
+         *
+         * Available only if @ref ConverterFeature::Preprocess is supported.
+         * First string is macro name, second its value. If the second string
+         * is empty (but not @cpp nullptr @ce), it's the same as
+         * @cpp #define @ce without a value; if the second string is
+         * @cpp nullptr @ce, it's the same as @cpp #undef @ce.
+         *
+         * Calling this function replaces the previous set, calling it with an
+         * empty list will reset the definitions back to initial state.
+         * @see @ref ConverterFlag::PreprocessOnly
+         */
+        void setDefinitions(Containers::ArrayView<const std::pair<Containers::StringView, Containers::StringView>> definitions);
+
+        /** @overload */
+        void setDefinitions(std::initializer_list<std::pair<Containers::StringView, Containers::StringView>> definitions);
+
         /**
          * @brief Validate a shader
          *
@@ -662,7 +696,9 @@ class MAGNUM_SHADERTOOLS_EXPORT AbstractConverter: public PluginManager::Abstrac
          *
          * Available only if @ref ConverterFeature::LinkData is supported. On
          * failure the function prints an error message and returns
-         * @cpp nullptr @ce.
+         * @cpp nullptr @ce. Can't be called if
+         * @ref ConverterFlag::PreprocessOnly is set --- in that case
+         * @ref convertDataToData() has to be used instead.
          * @see @ref features() @ref linkDataToFile(), @ref linkFilesToFile()
          */
         Containers::Array<char> linkDataToData(Containers::ArrayView<const std::pair<Stage, Containers::ArrayView<const void>>> data);
@@ -675,7 +711,9 @@ class MAGNUM_SHADERTOOLS_EXPORT AbstractConverter: public PluginManager::Abstrac
          *
          * Available only if @ref ConverterFeature::LinkData is supported. On
          * Returns @cpp true @ce on success, prints an error message and
-         * returns @cpp false @ce otherwise.
+         * returns @cpp false @ce otherwise. Can't be called if
+         * @ref ConverterFlag::PreprocessOnly is set --- in that case
+         * @ref convertDataToFile() has to be used instead.
          * @see @ref features(), @ref linkFilesToFile(),
          *      @ref linkFilesToData(), @ref linkDataToData()
          */
@@ -690,7 +728,9 @@ class MAGNUM_SHADERTOOLS_EXPORT AbstractConverter: public PluginManager::Abstrac
          * Available only if @ref ConverterFeature::LinkFile or
          * @ref ConverterFeature::LinkData is supported. Returns @cpp true @ce
          * on success, prints an error message and returns @cpp false @ce
-         * otherwise.
+         * otherwise. Can't be called if @ref ConverterFlag::PreprocessOnly is
+         * set --- in that case  @ref convertFileToFile() has to be used
+         * instead.
          * @see @ref features(), @ref linkFilesToData(), @ref linkDataToFile(),
          *      @ref linkDataToData()
          */
@@ -704,7 +744,9 @@ class MAGNUM_SHADERTOOLS_EXPORT AbstractConverter: public PluginManager::Abstrac
          *
          * Available only if @ref ConverterFeature::LinkData is supported, On
          * failure the function prints an error message and returns
-         * @cpp nullptr @ce.
+         * @cpp nullptr @ce. Can't be called if
+         * @ref ConverterFlag::PreprocessOnly is set --- in that case
+         * @ref convertFileToData() has to be used instead.
          * @see @ref features(), @ref linkFilesToFile(), @ref linkDataToFile(),
          *      @ref linkDataToData()
          */
@@ -862,6 +904,14 @@ class MAGNUM_SHADERTOOLS_EXPORT AbstractConverter: public PluginManager::Abstrac
          */
         virtual void doSetOutputFormat(Format format, Containers::StringView version) = 0;
 
+        /**
+         * @brief Implementation for @ref setDefinitions()
+         *
+         * Has to be implemented if @ref ConverterFeature::Preprocess is
+         * supported. This function isn't expected to fail.
+         */
+        virtual void doSetDefinitions(Containers::ArrayView<const std::pair<Containers::StringView, Containers::StringView>> definitions);
+
         /**
          * @brief Implementation for @ref validateData()
          *
diff --git a/src/Magnum/ShaderTools/Test/AbstractConverterTest.cpp b/src/Magnum/ShaderTools/Test/AbstractConverterTest.cpp
index fad87e037..a3cabc464 100644
--- a/src/Magnum/ShaderTools/Test/AbstractConverterTest.cpp
+++ b/src/Magnum/ShaderTools/Test/AbstractConverterTest.cpp
@@ -48,10 +48,16 @@ struct AbstractConverterTest: TestSuite::Tester {
 
     void setFlags();
     void setFlagsBothQuietAndVerbose();
+    void setFlagsPreprocessNotSupported();
+    void setFlagsPreprocessOnlyNotAllowed();
     void setFlagsNotImplemented();
 
     void setInputOutputFormat();
 
+    void setDefinitions();
+    void setDefinitionsNotSupported();
+    void setDefinitionsNotImplemented();
+
     void validateData();
     void validateDataNotSupported();
     void validateDataNotImplemented();
@@ -168,10 +174,16 @@ AbstractConverterTest::AbstractConverterTest() {
 
               &AbstractConverterTest::setFlags,
               &AbstractConverterTest::setFlagsBothQuietAndVerbose,
+              &AbstractConverterTest::setFlagsPreprocessNotSupported,
+              &AbstractConverterTest::setFlagsPreprocessOnlyNotAllowed,
               &AbstractConverterTest::setFlagsNotImplemented,
 
               &AbstractConverterTest::setInputOutputFormat,
 
+              &AbstractConverterTest::setDefinitions,
+              &AbstractConverterTest::setDefinitionsNotSupported,
+              &AbstractConverterTest::setDefinitionsNotImplemented,
+
               &AbstractConverterTest::validateData,
               &AbstractConverterTest::validateDataNotSupported,
               &AbstractConverterTest::validateDataNotImplemented,
@@ -294,7 +306,7 @@ void AbstractConverterTest::featuresNone() {
     struct: AbstractConverter {
         ConverterFeatures doFeatures() const override {
             /* These aren't real features, so it should still complain */
-            return ConverterFeature::InputFileCallback;
+            return ConverterFeature::InputFileCallback|ConverterFeature::Preprocess;
         }
         void doSetInputFormat(Format, Containers::StringView) override {}
         void doSetOutputFormat(Format, Containers::StringView) override {}
@@ -347,6 +359,55 @@ void AbstractConverterTest::setFlagsBothQuietAndVerbose() {
     CORRADE_COMPARE(out.str(), "ShaderTools::AbstractConverter::setFlags(): can't have both Quiet and Verbose set\n");
 }
 
+void AbstractConverterTest::setFlagsPreprocessNotSupported() {
+    #ifdef CORRADE_NO_ASSERT
+    CORRADE_SKIP("CORRADE_NO_ASSERT defined, can't test assertions");
+    #endif
+
+    struct: AbstractConverter {
+        ConverterFeatures doFeatures() const override {
+            return ConverterFeature::ValidateData;
+        }
+        void doSetInputFormat(Format, Containers::StringView) override {}
+        void doSetOutputFormat(Format, Containers::StringView) override {}
+    } converter;
+
+    std::ostringstream out;
+    Error redirectError{&out};
+    converter.setFlags(ConverterFlag::PreprocessOnly);
+    CORRADE_COMPARE(out.str(), "ShaderTools::AbstractConverter::setFlags(): PreprocessOnly not supported by the implementation\n");
+}
+
+void AbstractConverterTest::setFlagsPreprocessOnlyNotAllowed() {
+    #ifdef CORRADE_NO_ASSERT
+    CORRADE_SKIP("CORRADE_NO_ASSERT defined, can't test assertions");
+    #endif
+
+    struct: AbstractConverter {
+        ConverterFeatures doFeatures() const override {
+            /** @todo should Validate/Convert be enforced when Preprocess is
+                present? */
+            return ConverterFeature::Preprocess|ConverterFeature::LinkData;
+        }
+        void doSetInputFormat(Format, Containers::StringView) override {}
+        void doSetOutputFormat(Format, Containers::StringView) override {}
+    } converter;
+
+    converter.setFlags(ConverterFlag::PreprocessOnly);
+
+    std::ostringstream out;
+    Error redirectError{&out};
+    converter.linkDataToData({});
+    converter.linkDataToFile({}, {});
+    converter.linkFilesToFile({}, {});
+    converter.linkFilesToData({});
+    CORRADE_COMPARE(out.str(),
+        "ShaderTools::AbstractConverter::linkDataToData(): PreprocessOnly is not allowed in combination with linking\n"
+        "ShaderTools::AbstractConverter::linkDataToFile(): PreprocessOnly is not allowed in combination with linking\n"
+        "ShaderTools::AbstractConverter::linkFilesToFile(): PreprocessOnly is not allowed in combination with linking\n"
+        "ShaderTools::AbstractConverter::linkFilesToData(): PreprocessOnly is not allowed in combination with linking\n");
+}
+
 void AbstractConverterTest::setFlagsNotImplemented() {
     struct: AbstractConverter {
         ConverterFeatures doFeatures() const override {
@@ -396,6 +457,67 @@ void AbstractConverterTest::setInputOutputFormat() {
     CORRADE_COMPARE(converter.outputVersion, "");
 }
 
+void AbstractConverterTest::setDefinitions() {
+    struct: AbstractConverter {
+        ConverterFeatures doFeatures() const override {
+            return ConverterFeature::Preprocess|ConverterFeature::ValidateData;
+        }
+        void doSetInputFormat(Format, Containers::StringView) override {}
+        void doSetOutputFormat(Format, Containers::StringView) override {}
+
+        void doSetDefinitions(Containers::ArrayView<const std::pair<Containers::StringView, Containers::StringView>> definitions) override {
+            howManyIsThere = definitions.size();
+        }
+
+        std::size_t howManyIsThere = 0;
+    } converter;
+
+    converter.setDefinitions({
+        {"VULKAN", ""},
+        {"LIGHT_COUNT", "3"},
+        {"GL_ES", nullptr}
+    });
+    CORRADE_COMPARE(converter.howManyIsThere, 3);
+}
+
+void AbstractConverterTest::setDefinitionsNotSupported() {
+    #ifdef CORRADE_NO_ASSERT
+    CORRADE_SKIP("CORRADE_NO_ASSERT defined, can't test assertions");
+    #endif
+
+    struct: AbstractConverter {
+        ConverterFeatures doFeatures() const override {
+            return ConverterFeature::ValidateData;
+        }
+        void doSetInputFormat(Format, Containers::StringView) override {}
+        void doSetOutputFormat(Format, Containers::StringView) override {}
+    } converter;
+
+    std::ostringstream out;
+    Error redirectError{&out};
+    converter.setDefinitions({});
+    CORRADE_COMPARE(out.str(), "ShaderTools::AbstractConverter::setDefinitions(): feature not supported\n");
+}
+
+void AbstractConverterTest::setDefinitionsNotImplemented() {
+    #ifdef CORRADE_NO_ASSERT
+    CORRADE_SKIP("CORRADE_NO_ASSERT defined, can't test assertions");
+    #endif
+
+    struct: AbstractConverter {
+        ConverterFeatures doFeatures() const override {
+            return ConverterFeature::Preprocess|ConverterFeature::ValidateData;
+        }
+        void doSetInputFormat(Format, Containers::StringView) override {}
+        void doSetOutputFormat(Format, Containers::StringView) override {}
+    } converter;
+
+    std::ostringstream out;
+    Error redirectError{&out};
+    converter.setDefinitions({});
+    CORRADE_COMPARE(out.str(), "ShaderTools::AbstractConverter::setDefinitions(): feature advertised but not implemented\n");
+}
+
 void AbstractConverterTest::validateData() {
     struct: AbstractConverter {
         ConverterFeatures doFeatures() const override {