Index: clang-tidy/readability/FunctionSizeCheck.h
===================================================================
--- clang-tidy/readability/FunctionSizeCheck.h
+++ clang-tidy/readability/FunctionSizeCheck.h
@@ -27,6 +27,8 @@
 ///     macro-heavy code. The default is `800`.
 ///   * `BranchThreshold` - flag functions exceeding this number of control
 ///     statements. The default is `-1` (ignore the number of branches).
+///   * `ParameterThreshold` - flag functions having a high number of parameters.
+///     The default is `6`.
 class FunctionSizeCheck : public ClangTidyCheck {
 public:
   FunctionSizeCheck(StringRef Name, ClangTidyContext *Context);
@@ -39,6 +41,7 @@
   const unsigned LineThreshold;
   const unsigned StatementThreshold;
   const unsigned BranchThreshold;
+  const unsigned ParameterThreshold;
 };
 
 } // namespace readability
Index: clang-tidy/readability/FunctionSizeCheck.cpp
===================================================================
--- clang-tidy/readability/FunctionSizeCheck.cpp
+++ clang-tidy/readability/FunctionSizeCheck.cpp
@@ -72,12 +72,14 @@
     : ClangTidyCheck(Name, Context),
       LineThreshold(Options.get("LineThreshold", -1U)),
       StatementThreshold(Options.get("StatementThreshold", 800U)),
-      BranchThreshold(Options.get("BranchThreshold", -1U)) {}
+      BranchThreshold(Options.get("BranchThreshold", -1U)),
+      ParameterThreshold(Options.get("ParameterThreshold", 6)) {}
 
 void FunctionSizeCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
   Options.store(Opts, "LineThreshold", LineThreshold);
   Options.store(Opts, "StatementThreshold", StatementThreshold);
   Options.store(Opts, "BranchThreshold", BranchThreshold);
+  Options.store(Opts, "ParameterThreshold", ParameterThreshold);
 }
 
 void FunctionSizeCheck::registerMatchers(MatchFinder *Finder) {
@@ -103,8 +105,11 @@
     }
   }
 
+  unsigned ActualNumberParameters = Func->getNumParams();
+
   if (FI.Lines > LineThreshold || FI.Statements > StatementThreshold ||
-      FI.Branches > BranchThreshold) {
+      FI.Branches > BranchThreshold ||
+      ActualNumberParameters > ParameterThreshold) {
     diag(Func->getLocation(),
          "function %0 exceeds recommended size/complexity thresholds")
         << Func;
@@ -127,6 +132,12 @@
     diag(Func->getLocation(), "%0 branches (threshold %1)", DiagnosticIDs::Note)
         << FI.Branches << BranchThreshold;
   }
+
+  if (ActualNumberParameters > ParameterThreshold) {
+    diag(Func->getLocation(), "%0 parameters (threshold %1)",
+         DiagnosticIDs::Note)
+        << ActualNumberParameters << ParameterThreshold;
+  }
 }
 
 } // namespace readability
Index: docs/clang-tidy/checks/readability-function-size.rst
===================================================================
--- docs/clang-tidy/checks/readability-function-size.rst
+++ docs/clang-tidy/checks/readability-function-size.rst
@@ -25,3 +25,8 @@
 
    Flag functions exceeding this number of control statements. The default is
    `-1` (ignore the number of branches).
+
+.. option:: ParameterThreshold
+
+   Flag functions that exceed a specified number of parameters. The default 
+   is 6.
Index: test/clang-tidy/readability-function-size.cpp
===================================================================
--- test/clang-tidy/readability-function-size.cpp
+++ test/clang-tidy/readability-function-size.cpp
@@ -1,4 +1,6 @@
-// RUN: %check_clang_tidy %s readability-function-size %t -- -config='{CheckOptions: [{key: readability-function-size.LineThreshold, value: 0}, {key: readability-function-size.StatementThreshold, value: 0}, {key: readability-function-size.BranchThreshold, value: 0}]}' -- -std=c++11
+// RUN: %check_clang_tidy %s readability-function-size %t -- -config='{CheckOptions: [{key: readability-function-size.LineThreshold, value: 0}, {key: readability-function-size.StatementThreshold, value: 0}, {key: readability-function-size.BranchThreshold, value: 0}, {key: readability-function-size.ParameterThreshold, value: 5}]}' -- -std=c++11
+
+// Bad formatting is intentional, don't run clang-format over the whole file!
 
 void foo1() {
 }
@@ -37,6 +39,11 @@
 // CHECK-MESSAGES: :[[@LINE-4]]:25: note: 1 lines including whitespace and comments (threshold 0)
 // CHECK-MESSAGES: :[[@LINE-5]]:25: note: 1 statements (threshold 0)
 
+void foo7(int p1, int p2, int p3, int p4, int p5, int p6) {;}
+// CHECK-MESSAGES: :[[@LINE-1]]:6: warning: function 'foo7' exceeds recommended size/complexity
+// CHECK-MESSAGES: :[[@LINE-2]]:6: note: 1 statements (threshold 0)
+// CHECK-MESSAGES: :[[@LINE-3]]:6: note: 6 parameters (threshold 5)
+
 void bar1() { [](){;;;;;;;;;;;if(1){}}();