diff --git a/plugins/clang/codecompletion/completionhelper.cpp b/plugins/clang/codecompletion/completionhelper.cpp
--- a/plugins/clang/codecompletion/completionhelper.cpp
+++ b/plugins/clang/codecompletion/completionhelper.cpp
@@ -55,12 +55,33 @@
     QString templatePrefix;
 };
 
+QStringList templateParams(CXCursor cursor);
+
 CXChildVisitResult templateParamsHelper(CXCursor cursor, CXCursor /*parent*/, CXClientData data)
 {
     CXCursorKind kind = clang_getCursorKind(cursor);
-    if (kind == CXCursor_TemplateTypeParameter || kind == CXCursor_TemplateTemplateParameter ||
-        kind == CXCursor_NonTypeTemplateParameter) {
-        (*static_cast<QStringList*>(data)).append(ClangString(clang_getCursorSpelling(cursor)).toString());
+    auto& params = *static_cast<QStringList*>(data);
+    if (kind == CXCursor_TemplateTypeParameter) {
+        auto paramName = ClangString(clang_getCursorSpelling(cursor)).toString();
+        auto param = QStringLiteral("typename");
+        if (!paramName.isEmpty()) {
+            param += QLatin1Char(' ') + paramName;
+        }
+        params.append(param);
+    }
+    else if (kind == CXCursor_NonTypeTemplateParameter)	{
+        auto param = ClangString(clang_getTypeSpelling(clang_getCursorType(cursor))).toString();
+        auto paramName = ClangString(clang_getCursorSpelling(cursor)).toString();
+        if (!paramName.isEmpty()) {
+            param += QLatin1Char(' ') + paramName;
+        }
+        params.append(param);
+    }
+    else if (kind == CXCursor_TemplateTemplateParameter) {
+        auto paramName = ClangString(clang_getCursorSpelling(cursor)).toString();
+        auto templateTypes = templateParams(cursor);
+        auto param = QLatin1String("template<") + templateTypes.join(QStringLiteral(", ")) + QLatin1String("> class ") + paramName ;
+        params.append(param);
     }
     return CXChildVisit_Continue;
 }
@@ -247,7 +268,7 @@
                 //which goes at the front of the prototype
                 const QStringList templateTypes = templateParams(kind == CXCursor_ClassTemplate ? cursor : clang_getSpecializedCursorTemplate(cursor));
 
-                templatePrefix = QLatin1String("template<") + templateTypes.join(QStringLiteral(", typename ")) + QLatin1String("> ");
+                templatePrefix = QLatin1String("template<") + templateTypes.join(QStringLiteral(", ")) + QLatin1String("> ");
             }
         }
 
@@ -292,6 +313,12 @@
         return CXChildVisit_Continue;
     }
 
+    QString templatePrefix;
+    if (kind == CXCursor_FunctionTemplate) {
+        const QStringList templateTypes = templateParams(cursor);
+        templatePrefix = QLatin1String("template<") + templateTypes.join(QStringLiteral(", ")) + QLatin1String("> ");
+    }
+
     const auto scope = ClangUtils::getScope(cursor, data->origin);
     QString signature = ClangUtils::getCursorSignature(cursor, scope);
 
@@ -313,7 +340,7 @@
     }
     DeclarationPointer declaration = ClangHelpers::findDeclaration(clang_getCursorLocation(cursor), QualifiedIdentifier(), top);
     data->prototypes->append(FuncImplementInfo{kind == CXCursor_Constructor, kind == CXCursor_Destructor,
-                                               data->templatePrefix, returnType, rest, declaration});
+                                               data->templatePrefix + templatePrefix, returnType, rest, declaration});
 
     return CXChildVisit_Continue;
 }
diff --git a/plugins/clang/tests/test_codecompletion.cpp b/plugins/clang/tests/test_codecompletion.cpp
--- a/plugins/clang/tests/test_codecompletion.cpp
+++ b/plugins/clang/tests/test_codecompletion.cpp
@@ -831,6 +831,16 @@
             )"
         << CompletionItems{{5, 0}, {"Hello::bar()"}};
 
+    QTest::newRow("bug368544")
+        << R"(
+                class Klass {
+                public:
+                    template <typename T>
+                    void func(int a, T x, int b) const;
+                };
+            )"
+        << CompletionItems{{6, 0}, {"Klass::func(int a, T x, int b) const"}};
+
 }
 
 void TestCodeCompletion::testImplementOtherFile()
@@ -1360,6 +1370,24 @@
         << CompletionItems({6, 5}, {"Blue", "Green", "Red", "Yellow"})
         << "Yellow"
         << "enum class Color {\nBlue, Green, Red, Yellow\n};\nvoid foo() {\nColor x;\nswitch (x) {\ncase Color::Yellow: break;}\n}";
+
+    QTest::newRow("bug368544")
+        << "class Klass {\npublic:\ntemplate <typename T>\nvoid func(int a, T x, int b) const;\n};\n"
+        << CompletionItems({5, 0}, {"Klass", "Klass::func(int a, T x, int b) const"})
+        << "Klass::func(int a, T x, int b) const"
+        << "class Klass {\npublic:\ntemplate <typename T>\nvoid func(int a, T x, int b) const;\n};\ntemplate<typename T> void Klass::func(int a, T x, int b) const\n{\n}\n";
+
+    QTest::newRow("bug377397")
+        << "template<typename T> class Foo {\nvoid bar();\n};\n"
+        << CompletionItems({3, 0}, {"Foo", "Foo<T>::bar()"})
+        << "Foo<T>::bar()"
+        << "template<typename T> class Foo {\nvoid bar();\n};\ntemplate<typename T> void Foo<T>::bar()\n{\n}\n";
+
+    QTest::newRow("template-template-parameter")
+        << "template <template<class, int> class X, typename B>\nclass Test {\npublic:\nvoid bar(B a);\n};\n"
+        << CompletionItems({5, 0}, {"Test", "Test<X, B>::bar(B a)"})
+        << "Test<X, B>::bar(B a)"
+        << "template <template<class, int> class X, typename B>\nclass Test {\npublic:\nvoid bar(B a);\n};\ntemplate<template<typename, int> class X, typename B> void Test<X, B>::bar(B a)\n{\n}\n";
 }
 
 void TestCodeCompletion::testIgnoreGccBuiltins()
diff --git a/plugins/clang/util/clangutils.cpp b/plugins/clang/util/clangutils.cpp
--- a/plugins/clang/util/clangutils.cpp
+++ b/plugins/clang/util/clangutils.cpp
@@ -244,9 +244,34 @@
 
     //Add the parameters and such
     stream << '(';
-    int numArgs = clang_Cursor_getNumArguments(cursor);
+    int numArgs ;
+    QVector<CXCursor> args;
+
+    // SEE https://bugs.kde.org/show_bug.cgi?id=368544
+    // clang_Cursor_getNumArguments returns -1 for FunctionTemplate
+    // clang checks if cursor's Decl is ObjCMethodDecl or FunctionDecl
+    // CXCursor_FunctionTemplate is neither of them instead it has a FunctionTemplateDecl
+    // HACK Get function template arguments by visiting children
+    if (kind == CXCursor_FunctionTemplate) {
+        clang_visitChildren(cursor, [] (CXCursor cursor, CXCursor /*parent*/, CXClientData data) {
+            if (clang_getCursorKind(cursor) == CXCursor_ParmDecl) {
+                (static_cast<QVector<CXCursor>*>(data))->push_back(cursor);
+            }
+            return CXChildVisit_Continue;
+        }, &args);
+        numArgs = args.size();
+    }
+    else {
+        numArgs = clang_Cursor_getNumArguments(cursor);
+        args.reserve(numArgs);
+        for (int i = 0; i < numArgs; i++) {
+            CXCursor arg = clang_Cursor_getArgument(cursor, i);
+            args.push_back(arg);
+        }
+    }
+
     for (int i = 0; i < numArgs; i++) {
-        CXCursor arg = clang_Cursor_getArgument(cursor, i);
+        CXCursor arg = args[i];
 
         //Clang formats pointer types as "t *x" and reference types as "t &x", while
         //KDevelop formats them as "t* x" and "t& x". Make that adjustment.