diff --git a/openmp/runtime/src/kmp.h b/openmp/runtime/src/kmp.h
index fc2facc38f34..07fc8642836f 100644
--- a/openmp/runtime/src/kmp.h
+++ b/openmp/runtime/src/kmp.h
@@ -3183,7 +3183,7 @@ extern void __kmp_aux_set_stacksize( size_t arg);
 extern void __kmp_aux_set_blocktime (int arg, kmp_info_t *thread, int tid);
 extern void __kmp_aux_set_defaults( char const * str, int len );
 
-/* Functions below put here to call them from __kmp_aux_env_initialize() in kmp_settings.c */
+/* Functions called from __kmp_aux_env_initialize() in kmp_settings.cpp */
 void kmpc_set_blocktime (int arg);
 void ompc_set_nested( int flag );
 void ompc_set_dynamic( int flag );
diff --git a/openmp/runtime/src/kmp_alloc.cpp b/openmp/runtime/src/kmp_alloc.cpp
index f3665eca1b8b..9e7ed3f1fe2a 100644
--- a/openmp/runtime/src/kmp_alloc.cpp
+++ b/openmp/runtime/src/kmp_alloc.cpp
@@ -1,5 +1,5 @@
 /*
- * kmp_alloc.c -- private/shared dynamic memory allocation and management
+ * kmp_alloc.cpp -- private/shared dynamic memory allocation and management
  */
 
 
diff --git a/openmp/runtime/src/kmp_atomic.cpp b/openmp/runtime/src/kmp_atomic.cpp
index fec2f88c6c09..3831165d0d7a 100644
--- a/openmp/runtime/src/kmp_atomic.cpp
+++ b/openmp/runtime/src/kmp_atomic.cpp
@@ -1,5 +1,5 @@
 /*
- * kmp_atomic.c -- ATOMIC implementation routines
+ * kmp_atomic.cpp -- ATOMIC implementation routines
  */
 
 
diff --git a/openmp/runtime/src/kmp_csupport.cpp b/openmp/runtime/src/kmp_csupport.cpp
index 00dc47167a39..a52f4ece8e29 100644
--- a/openmp/runtime/src/kmp_csupport.cpp
+++ b/openmp/runtime/src/kmp_csupport.cpp
@@ -1,5 +1,5 @@
 /*
- * kmp_csupport.c -- kfront linkage support for OpenMP.
+ * kmp_csupport.cpp -- kfront linkage support for OpenMP.
  */
 
 
@@ -464,9 +464,10 @@ when the condition is false.
 void
 __kmpc_serialized_parallel(ident_t *loc, kmp_int32 global_tid)
 {
-    __kmp_serialized_parallel(loc, global_tid); /* The implementation is now in kmp_runtime.c so that it can share static functions with
-                                                 * kmp_fork_call since the tasks to be done are similar in each case.
-                                                 */
+    // The implementation is now in kmp_runtime.cpp so that it can share static
+    // functions with kmp_fork_call since the tasks to be done are similar in
+    // each case.
+    __kmp_serialized_parallel(loc, global_tid);
 }
 
 /*!
diff --git a/openmp/runtime/src/kmp_debug.cpp b/openmp/runtime/src/kmp_debug.cpp
index 3bbffa53f21c..fd7b905bcc45 100644
--- a/openmp/runtime/src/kmp_debug.cpp
+++ b/openmp/runtime/src/kmp_debug.cpp
@@ -1,5 +1,5 @@
 /*
- * kmp_debug.c -- debug utilities for the Guide library
+ * kmp_debug.cpp -- debug utilities for the Guide library
  */
 
 
diff --git a/openmp/runtime/src/kmp_dispatch.cpp b/openmp/runtime/src/kmp_dispatch.cpp
index 4df22ed68c80..305839b423da 100644
--- a/openmp/runtime/src/kmp_dispatch.cpp
+++ b/openmp/runtime/src/kmp_dispatch.cpp
@@ -2616,7 +2616,7 @@ __kmpc_dispatch_fini_8u( ident_t *loc, kmp_int32 gtid )
 /*! @} */
 
 //-----------------------------------------------------------------------------------------
-//Non-template routines from kmp_dispatch.c used in other sources
+//Non-template routines from kmp_dispatch.cpp used in other sources
 
 kmp_uint32 __kmp_eq_4( kmp_uint32 value, kmp_uint32 checker) {
     return value == checker;
diff --git a/openmp/runtime/src/kmp_environment.cpp b/openmp/runtime/src/kmp_environment.cpp
index 940235a92980..d4d95dfc39c6 100644
--- a/openmp/runtime/src/kmp_environment.cpp
+++ b/openmp/runtime/src/kmp_environment.cpp
@@ -1,5 +1,5 @@
 /*
- * kmp_environment.c -- Handle environment variables OS-independently.
+ * kmp_environment.cpp -- Handle environment variables OS-independently.
  */
 
 
diff --git a/openmp/runtime/src/kmp_error.cpp b/openmp/runtime/src/kmp_error.cpp
index 6866df5d4962..2d84066817ac 100644
--- a/openmp/runtime/src/kmp_error.cpp
+++ b/openmp/runtime/src/kmp_error.cpp
@@ -1,5 +1,5 @@
 /*
- * kmp_error.c -- KPTS functions for error checking at runtime
+ * kmp_error.cpp -- KPTS functions for error checking at runtime
  */
 
 
diff --git a/openmp/runtime/src/kmp_ftn_cdecl.cpp b/openmp/runtime/src/kmp_ftn_cdecl.cpp
index 5844bee85bc5..a3c37796aa35 100644
--- a/openmp/runtime/src/kmp_ftn_cdecl.cpp
+++ b/openmp/runtime/src/kmp_ftn_cdecl.cpp
@@ -1,5 +1,5 @@
 /*
- * kmp_ftn_cdecl.c -- Fortran __cdecl linkage support for OpenMP.
+ * kmp_ftn_cdecl.cpp -- Fortran __cdecl linkage support for OpenMP.
  */
 
 
diff --git a/openmp/runtime/src/kmp_ftn_extra.cpp b/openmp/runtime/src/kmp_ftn_extra.cpp
index 73c4e2d45b7a..8acd3734761e 100644
--- a/openmp/runtime/src/kmp_ftn_extra.cpp
+++ b/openmp/runtime/src/kmp_ftn_extra.cpp
@@ -1,5 +1,5 @@
 /*
- * kmp_ftn_extra.c -- Fortran 'extra' linkage support for OpenMP.
+ * kmp_ftn_extra.cpp -- Fortran 'extra' linkage support for OpenMP.
  */
 
 
diff --git a/openmp/runtime/src/kmp_ftn_stdcall.cpp b/openmp/runtime/src/kmp_ftn_stdcall.cpp
index cf70d74af553..41f04de72853 100644
--- a/openmp/runtime/src/kmp_ftn_stdcall.cpp
+++ b/openmp/runtime/src/kmp_ftn_stdcall.cpp
@@ -1,5 +1,5 @@
 /*
- * kmp_ftn_stdcall.c -- Fortran __stdcall linkage support for OpenMP.
+ * kmp_ftn_stdcall.cpp -- Fortran __stdcall linkage support for OpenMP.
  */
 
 
diff --git a/openmp/runtime/src/kmp_global.cpp b/openmp/runtime/src/kmp_global.cpp
index 86cd3d204eeb..5e73f87c31ed 100644
--- a/openmp/runtime/src/kmp_global.cpp
+++ b/openmp/runtime/src/kmp_global.cpp
@@ -1,5 +1,5 @@
 /*
- * kmp_global.c -- KPTS global variables for runtime support library
+ * kmp_global.cpp -- KPTS global variables for runtime support library
  */
 
 
diff --git a/openmp/runtime/src/kmp_gsupport.cpp b/openmp/runtime/src/kmp_gsupport.cpp
index e07c09d3c2e3..2c6d097550a2 100644
--- a/openmp/runtime/src/kmp_gsupport.cpp
+++ b/openmp/runtime/src/kmp_gsupport.cpp
@@ -1,5 +1,5 @@
 /*
- * kmp_gsupport.c
+ * kmp_gsupport.cpp
  */
 
 
diff --git a/openmp/runtime/src/kmp_i18n.cpp b/openmp/runtime/src/kmp_i18n.cpp
index 538c5f3279ed..ea4f30e13854 100644
--- a/openmp/runtime/src/kmp_i18n.cpp
+++ b/openmp/runtime/src/kmp_i18n.cpp
@@ -1,5 +1,5 @@
 /*
- * kmp_i18n.c
+ * kmp_i18n.cpp
  */
 
 
diff --git a/openmp/runtime/src/kmp_import.cpp b/openmp/runtime/src/kmp_import.cpp
index 42fba412c1f4..fc4bdae9dbe3 100644
--- a/openmp/runtime/src/kmp_import.cpp
+++ b/openmp/runtime/src/kmp_import.cpp
@@ -1,5 +1,5 @@
 /*
- * kmp_import.c
+ * kmp_import.cpp
  */
 
 
diff --git a/openmp/runtime/src/kmp_io.cpp b/openmp/runtime/src/kmp_io.cpp
index 4e79e22efe68..88a2c15377c2 100644
--- a/openmp/runtime/src/kmp_io.cpp
+++ b/openmp/runtime/src/kmp_io.cpp
@@ -1,5 +1,5 @@
 /*
- * KMP_IO.c -- RTL IO
+ * kmp_io.cpp -- RTL IO
  */
 
 
diff --git a/openmp/runtime/src/kmp_itt.cpp b/openmp/runtime/src/kmp_itt.cpp
index 3eb548604a11..56d7e6796a7a 100644
--- a/openmp/runtime/src/kmp_itt.cpp
+++ b/openmp/runtime/src/kmp_itt.cpp
@@ -2,7 +2,7 @@
 
 #if USE_ITT_BUILD
 /*
- * kmp_itt.c -- ITT Notify interface.
+ * kmp_itt.cpp -- ITT Notify interface.
  */
 
 
diff --git a/openmp/runtime/src/kmp_lock.cpp b/openmp/runtime/src/kmp_lock.cpp
index a1c258333b84..0055116471c6 100644
--- a/openmp/runtime/src/kmp_lock.cpp
+++ b/openmp/runtime/src/kmp_lock.cpp
@@ -2528,7 +2528,7 @@ __kmp_acquire_drdpa_lock_timed_template( kmp_drdpa_lock_t *lck, kmp_int32 gtid )
     // polling area has been reconfigured.  Unless it is reconfigured, the
     // reloads stay in L1 cache and are cheap.
     //
-    // Keep this code in sync with KMP_WAIT_YIELD, in kmp_dispatch.c !!!
+    // Keep this code in sync with KMP_WAIT_YIELD, in kmp_dispatch.cpp !!!
     //
     // The current implementation of KMP_WAIT_YIELD doesn't allow for mask
     // and poll to be re-read every spin iteration.
@@ -3522,7 +3522,7 @@ __kmp_test_indirect_lock_with_checks(kmp_dyna_lock_t * lock, kmp_int32 gtid)
 
 kmp_dyna_lockseq_t __kmp_user_lock_seq = lockseq_queuing;
 
-// This is used only in kmp_error.c when consistency checking is on.
+// This is used only in kmp_error.cpp when consistency checking is on.
 kmp_int32
 __kmp_get_user_lock_owner(kmp_user_lock_p lck, kmp_uint32 seq)
 {
diff --git a/openmp/runtime/src/kmp_lock.h b/openmp/runtime/src/kmp_lock.h
index 4d0a2f272cd7..2f4f65f2caf2 100644
--- a/openmp/runtime/src/kmp_lock.h
+++ b/openmp/runtime/src/kmp_lock.h
@@ -1287,7 +1287,7 @@ extern int __kmp_num_locks_in_block;
                                ? KMP_GET_I_LOCK(KMP_EXTRACT_I_INDEX(l)) \
                                : *((kmp_indirect_lock_t **)(l)) )
 
-// Used once in kmp_error.c
+// Used once in kmp_error.cpp
 extern kmp_int32
 __kmp_get_user_lock_owner(kmp_user_lock_p, kmp_uint32);
 
diff --git a/openmp/runtime/src/kmp_runtime.cpp b/openmp/runtime/src/kmp_runtime.cpp
index 2a67206f9810..e8626d166156 100644
--- a/openmp/runtime/src/kmp_runtime.cpp
+++ b/openmp/runtime/src/kmp_runtime.cpp
@@ -1,5 +1,5 @@
 /*
- * kmp_runtime.c -- KPTS runtime support library
+ * kmp_runtime.cpp -- KPTS runtime support library
  */
 
 
diff --git a/openmp/runtime/src/kmp_sched.cpp b/openmp/runtime/src/kmp_sched.cpp
index b6f30812b1b0..ee6bb67df1a6 100644
--- a/openmp/runtime/src/kmp_sched.cpp
+++ b/openmp/runtime/src/kmp_sched.cpp
@@ -1,5 +1,5 @@
 /*
- * kmp_sched.c -- static scheduling -- iteration initialization
+ * kmp_sched.cpp -- static scheduling -- iteration initialization
  */
 
 
diff --git a/openmp/runtime/src/kmp_settings.cpp b/openmp/runtime/src/kmp_settings.cpp
index ef7f69eef249..9dd86512048c 100644
--- a/openmp/runtime/src/kmp_settings.cpp
+++ b/openmp/runtime/src/kmp_settings.cpp
@@ -1,5 +1,5 @@
 /*
- * kmp_settings.c -- Initialize environment variables
+ * kmp_settings.cpp -- Initialize environment variables
  */
 
 
diff --git a/openmp/runtime/src/kmp_str.cpp b/openmp/runtime/src/kmp_str.cpp
index c9f913c0bdce..8d633adb5d95 100644
--- a/openmp/runtime/src/kmp_str.cpp
+++ b/openmp/runtime/src/kmp_str.cpp
@@ -1,5 +1,5 @@
 /*
- * kmp_str.c -- String manipulation routines.
+ * kmp_str.cpp -- String manipulation routines.
  */
 
 
diff --git a/openmp/runtime/src/kmp_stub.cpp b/openmp/runtime/src/kmp_stub.cpp
index 437bf3d538a6..11b7cb60c2c7 100644
--- a/openmp/runtime/src/kmp_stub.cpp
+++ b/openmp/runtime/src/kmp_stub.cpp
@@ -1,5 +1,5 @@
 /*
- * kmp_stub.c -- stub versions of user-callable OpenMP RT functions.
+ * kmp_stub.cpp -- stub versions of user-callable OpenMP RT functions.
  */
 
 
@@ -56,16 +56,16 @@ static size_t __kmps_init() {
     static size_t dummy = 0;
     if ( ! initialized ) {
 
-        // TODO: Analyze KMP_VERSION environment variable, print __kmp_version_copyright and
-        // __kmp_version_build_time.
-        // WARNING: Do not use "fprintf( stderr, ... )" because it will cause unresolved "__iob"
-        // symbol (see C70080). We need to extract __kmp_printf() stuff from kmp_runtime.c and use
-        // it.
+        // TODO: Analyze KMP_VERSION environment variable, print
+        // __kmp_version_copyright and __kmp_version_build_time.
+        // WARNING: Do not use "fprintf( stderr, ... )" because it will cause
+        // unresolved "__iob" symbol (see C70080). We need to extract
+        // __kmp_printf() stuff from kmp_runtime.cpp and use it.
 
-        // Trick with dummy variable forces linker to keep __kmp_version_copyright and
-        // __kmp_version_build_time strings in executable file (in case of static linkage).
-        // When KMP_VERSION analyze is implemented, dummy variable should be deleted, function
-        // should return void.
+        // Trick with dummy variable forces linker to keep __kmp_version_copyright
+        // and __kmp_version_build_time strings in executable file (in case of
+        // static linkage). When KMP_VERSION analysis is implemented, dummy
+        // variable should be deleted, function should return void.
         dummy = __kmp_version_copyright - __kmp_version_build_time;
 
         #if KMP_OS_WINDOWS
diff --git a/openmp/runtime/src/kmp_tasking.cpp b/openmp/runtime/src/kmp_tasking.cpp
index 07557890c4d8..4018b2d8f9ea 100644
--- a/openmp/runtime/src/kmp_tasking.cpp
+++ b/openmp/runtime/src/kmp_tasking.cpp
@@ -1,5 +1,5 @@
 /*
- * kmp_tasking.c -- OpenMP 3.0 tasking support.
+ * kmp_tasking.cpp -- OpenMP 3.0 tasking support.
  */
 
 
diff --git a/openmp/runtime/src/kmp_taskq.cpp b/openmp/runtime/src/kmp_taskq.cpp
index 3079d45974b0..b07bda862fec 100644
--- a/openmp/runtime/src/kmp_taskq.cpp
+++ b/openmp/runtime/src/kmp_taskq.cpp
@@ -1,5 +1,5 @@
 /*
- * kmp_taskq.c -- TASKQ support for OpenMP.
+ * kmp_taskq.cpp -- TASKQ support for OpenMP.
  */
 
 
diff --git a/openmp/runtime/src/kmp_threadprivate.cpp b/openmp/runtime/src/kmp_threadprivate.cpp
index 2a18d808e62e..31d3e07508d9 100644
--- a/openmp/runtime/src/kmp_threadprivate.cpp
+++ b/openmp/runtime/src/kmp_threadprivate.cpp
@@ -1,5 +1,5 @@
 /*
- * kmp_threadprivate.c -- OpenMP threadprivate support library
+ * kmp_threadprivate.cpp -- OpenMP threadprivate support library
  */
 
 
diff --git a/openmp/runtime/src/kmp_utility.cpp b/openmp/runtime/src/kmp_utility.cpp
index 761fd06ac2e5..a5244b076129 100644
--- a/openmp/runtime/src/kmp_utility.cpp
+++ b/openmp/runtime/src/kmp_utility.cpp
@@ -1,5 +1,5 @@
 /*
- * kmp_utility.c -- Utility routines for the OpenMP support library.
+ * kmp_utility.cpp -- Utility routines for the OpenMP support library.
  */
 
 
diff --git a/openmp/runtime/src/kmp_version.cpp b/openmp/runtime/src/kmp_version.cpp
index 15edfd2fd426..8b782b320af5 100644
--- a/openmp/runtime/src/kmp_version.cpp
+++ b/openmp/runtime/src/kmp_version.cpp
@@ -1,5 +1,5 @@
 /*
- * kmp_version.c
+ * kmp_version.cpp
  */
 
 
diff --git a/openmp/runtime/src/tsan_annotations.cpp b/openmp/runtime/src/tsan_annotations.cpp
index edc4e7c97093..9d055555867a 100644
--- a/openmp/runtime/src/tsan_annotations.cpp
+++ b/openmp/runtime/src/tsan_annotations.cpp
@@ -1,5 +1,5 @@
 /*
- * tsan_annotations.c -- ThreadSanitizer annotations to support data
+ * tsan_annotations.cpp -- ThreadSanitizer annotations to support data
  * race detection in OpenMP programs.
  */
 
diff --git a/openmp/runtime/src/z_Linux_util.cpp b/openmp/runtime/src/z_Linux_util.cpp
index 34a4f2c97690..b9490ea65d39 100644
--- a/openmp/runtime/src/z_Linux_util.cpp
+++ b/openmp/runtime/src/z_Linux_util.cpp
@@ -1,5 +1,5 @@
 /*
- * z_Linux_util.c -- platform specific routines.
+ * z_Linux_util.cpp -- platform specific routines.
  */
 
 
@@ -1503,7 +1503,7 @@ __kmp_atfork_child (void)
        Suggestion is to make the library initialization lazier, similar
        to what done for __kmpc_begin(). */
     // TODO: synchronize all static initializations with regular library
-    //       startup; look at kmp_global.c and etc.
+    //       startup; look at kmp_global.cpp and etc.
     //__kmp_internal_begin ();
 
 }
diff --git a/openmp/runtime/src/z_Windows_NT-586_util.cpp b/openmp/runtime/src/z_Windows_NT-586_util.cpp
index 3aeafae9102b..d7697d5a1be6 100644
--- a/openmp/runtime/src/z_Windows_NT-586_util.cpp
+++ b/openmp/runtime/src/z_Windows_NT-586_util.cpp
@@ -1,5 +1,5 @@
 /*
- * z_Windows_NT-586_util.c -- platform specific routines.
+ * z_Windows_NT-586_util.cpp -- platform specific routines.
  */
 
 
diff --git a/openmp/runtime/src/z_Windows_NT_util.cpp b/openmp/runtime/src/z_Windows_NT_util.cpp
index 1a371303e1a9..aa1edac0ff00 100644
--- a/openmp/runtime/src/z_Windows_NT_util.cpp
+++ b/openmp/runtime/src/z_Windows_NT_util.cpp
@@ -1,5 +1,5 @@
 /*
- * z_Windows_NT_util.c -- platform specific routines.
+ * z_Windows_NT_util.cpp -- platform specific routines.
  */