Index: docs/clang-tidy/checks/misc-definitions-in-headers.rst
===================================================================
--- docs/clang-tidy/checks/misc-definitions-in-headers.rst
+++ docs/clang-tidy/checks/misc-definitions-in-headers.rst
@@ -82,6 +82,8 @@
 
    constexpr int k = 1; // OK: constexpr variable has internal linkage.
 
+   constexpr int f10() { return 0; } // OK: constexpr function definition.
+
 Options
 -------
 
Index: test/clang-tidy/check_clang_tidy.py
===================================================================
--- test/clang-tidy/check_clang_tidy.py
+++ test/clang-tidy/check_clang_tidy.py
@@ -58,8 +58,8 @@
 
   clang_tidy_extra_args = extra_args
   if len(clang_tidy_extra_args) == 0:
-    clang_tidy_extra_args = ['--', '--std=c++11'] if extension == '.cpp' \
-                       else ['--']
+    clang_tidy_extra_args = ['--', '--std=c++11'] \
+        if extension == '.cpp' or extension == '.hpp' else ['--']
 
   # Tests should not rely on STL being available, and instead provide mock
   # implementations of relevant APIs.
Index: test/clang-tidy/misc-definitions-in-headers.hpp
===================================================================
--- test/clang-tidy/misc-definitions-in-headers.hpp
+++ test/clang-tidy/misc-definitions-in-headers.hpp
@@ -1,4 +1,4 @@
-// RUN: %check_clang_tidy %s misc-definitions-in-headers %t -- -- -std=c++11
+// RUN: %check_clang_tidy %s misc-definitions-in-headers %t
 
 int f() {
 // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: function 'f' defined in a header file; function definitions in header files can lead to ODR violations [misc-definitions-in-headers]
@@ -177,3 +177,5 @@
 }
 
 constexpr int k = 1; // OK: constexpr variable has internal linkage.
+
+constexpr int f10() { return 0; } // OK: constexpr function definition.