diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -576,20 +576,20 @@
   "thread-local storage is not supported for the current target">;
 
 def warn_maybe_falloff_nonvoid_function : Warning<
-  "control may reach end of non-void function">,
+  "non-void function does not return a value in all control paths">,
   InGroup<ReturnType>;
 def warn_falloff_nonvoid_function : Warning<
-  "control reaches end of non-void function">,
+  "non-void function does not return a value">,
   InGroup<ReturnType>;
 def err_maybe_falloff_nonvoid_block : Error<
-  "control may reach end of non-void block">;
+  "non-void block does not return a value in all control paths">;
 def err_falloff_nonvoid_block : Error<
-  "control reaches end of non-void block">;
+  "non-void block does not return a value">;
 def warn_maybe_falloff_nonvoid_coroutine : Warning<
-  "control may reach end of coroutine; which is undefined behavior because the promise type %0 does not declare 'return_void()'">,
+  "non-void coroutine does not return a value in all control paths">,
   InGroup<ReturnType>;
 def warn_falloff_nonvoid_coroutine : Warning<
-  "control reaches end of coroutine; which is undefined behavior because the promise type %0 does not declare 'return_void()'">,
+  "non-void coroutine does not return a value">,
   InGroup<ReturnType>;
 def warn_suggest_noreturn_function : Warning<
   "%select{function|method}0 %1 could be declared with attribute 'noreturn'">,
@@ -6858,10 +6858,10 @@
   def err_noreturn_lambda_has_return_expr : Error<
     "lambda declared 'noreturn' should not return">;
   def warn_maybe_falloff_nonvoid_lambda : Warning<
-    "control may reach end of non-void lambda">,
+    "non-void lambda does not return a value in all control paths">,
     InGroup<ReturnType>;
   def warn_falloff_nonvoid_lambda : Warning<
-    "control reaches end of non-void lambda">,
+    "non-void lambda does not return a value">,
     InGroup<ReturnType>;
   def err_access_lambda_capture : Error<
     // The ERRORs represent other special members that aren't constructors, in
diff --git a/clang/test/Sema/block-return-1.c b/clang/test/Sema/block-return-1.c
--- a/clang/test/Sema/block-return-1.c
+++ b/clang/test/Sema/block-return-1.c
@@ -2,5 +2,5 @@
 
 int j;
 void foo() {
-  ^ (void) { if (j) return 1; }(); // expected-error {{control may reach end of non-void block}}
+  ^ (void) { if (j) return 1; }(); // expected-error {{non-void block does not return a value in all control paths}}
 }
diff --git a/clang/test/Sema/block-return-3.c b/clang/test/Sema/block-return-3.c
--- a/clang/test/Sema/block-return-3.c
+++ b/clang/test/Sema/block-return-3.c
@@ -1,5 +1,5 @@
 // RUN: %clang_cc1 -fsyntax-only %s -verify -fblocks
 
 void foo() {
-  ^ int (void) { }(); // expected-error {{control reaches end of non-void block}}
+  ^ int (void) { }(); // expected-error {{non-void block does not return a value}}
 }
diff --git a/clang/test/Sema/freemain.c b/clang/test/Sema/freemain.c
--- a/clang/test/Sema/freemain.c
+++ b/clang/test/Sema/freemain.c
@@ -6,4 +6,4 @@
 
 void* main(void* context, long size) {
   if (context) return allocate(size);
-} // expected-warning {{control may reach end of non-void function}}
+} // expected-warning {{non-void function does not return a value in all control paths}}
diff --git a/clang/test/Sema/return.c b/clang/test/Sema/return.c
--- a/clang/test/Sema/return.c
+++ b/clang/test/Sema/return.c
@@ -17,7 +17,7 @@
 }
 
 int test1() {
-} // expected-warning {{control reaches end of non-void function}}
+} // expected-warning {{non-void function does not return a value}}
 
 int test2() {
   a: goto a;
@@ -26,7 +26,7 @@
 int test3() {
   goto a;
   a: ;
-} // expected-warning {{control reaches end of non-void function}}
+} // expected-warning {{non-void function does not return a value}}
 
 
 void halt() {
@@ -54,11 +54,11 @@
 
 int test7() {
   unknown();
-} // expected-warning {{control reaches end of non-void function}}
+} // expected-warning {{non-void function does not return a value}}
 
 int test8() {
   (void)(1 + unknown());
-} // expected-warning {{control reaches end of non-void function}}
+} // expected-warning {{non-void function does not return a value}}
 
 int halt3() __attribute__((noreturn));
 
@@ -68,11 +68,11 @@
 
 int test10() {
   (void)(unknown() || halt3());
-} // expected-warning {{control may reach end of non-void function}}
+} // expected-warning {{non-void function does not return a value in all control paths}}
 
 int test11() {
   (void)(unknown() && halt3());
-} // expected-warning {{control may reach end of non-void function}}
+} // expected-warning {{non-void function does not return a value in all control paths}}
 
 int test12() {
   (void)(halt3() || unknown());
@@ -84,27 +84,27 @@
 
 int test14() {
   (void)(1 || unknown());
-} // expected-warning {{control reaches end of non-void function}}
+} // expected-warning {{non-void function does not return a value}}
 
 int test15() {
   (void)(0 || unknown());
-} // expected-warning {{control reaches end of non-void function}}
+} // expected-warning {{non-void function does not return a value}}
 
 int test16() {
   (void)(0 && unknown());
-} // expected-warning {{control reaches end of non-void function}}
+} // expected-warning {{non-void function does not return a value}}
 
 int test17() {
   (void)(1 && unknown());
-} // expected-warning {{control reaches end of non-void function}}
+} // expected-warning {{non-void function does not return a value}}
 
 int test18() {
   (void)(unknown_nohalt() && halt3());
-} // expected-warning {{control may reach end of non-void function}}
+} // expected-warning {{non-void function does not return a value in all control paths}}
 
 int test19() {
   (void)(unknown_nohalt() && unknown());
-} // expected-warning {{control reaches end of non-void function}}
+} // expected-warning {{non-void function does not return a value}}
 
 int test20() {
   int i;
@@ -112,7 +112,7 @@
     return 0;
   else if (0)
     return 2;
-} // expected-warning {{control may reach end of non-void function}}
+} // expected-warning {{non-void function does not return a value in all control paths}}
 
 int test21() {
   int i;
@@ -125,7 +125,7 @@
 int test22() {
   int i;
   switch (i) default: ;
-} // expected-warning {{control reaches end of non-void function}}
+} // expected-warning {{non-void function does not return a value}}
 
 int test23() {
   int i;
@@ -135,7 +135,7 @@
   case 2:
     return 2;
   }
-} // expected-warning {{control may reach end of non-void function}}
+} // expected-warning {{non-void function does not return a value in all control paths}}
 
 int test24() {
   int i;
@@ -155,7 +155,7 @@
 
 int test26() {
   0 ? halt3() : unknown();
-} // expected-warning {{control reaches end of non-void function}}
+} // expected-warning {{non-void function does not return a value}}
 
 int j;
 void (*fptr)() __attribute__((noreturn));
@@ -231,19 +231,19 @@
 
 // Test that 'static inline' functions are only analyzed for CFG-based warnings
 // when they are used.
-static inline int si_has_missing_return() {} // expected-warning{{control reaches end of non-void function}}
-static inline int si_has_missing_return_2() {}; // expected-warning{{control reaches end of non-void function}}
+static inline int si_has_missing_return() {} // expected-warning{{non-void function does not return a value}}
+static inline int si_has_missing_return_2() {}; // expected-warning{{non-void function does not return a value}}
 static inline int si_forward();
 static inline int si_has_missing_return_3(int x) {
   if (x)
    return si_has_missing_return_3(x+1);
-} // expected-warning{{control may reach end of non-void function}}
+} // expected-warning{{non-void function does not return a value in all control paths}}
 
 int test_static_inline(int x) {
   si_forward();
   return x ? si_has_missing_return_2() : si_has_missing_return_3(x);
 }
-static inline int si_forward() {} // expected-warning{{control reaches end of non-void function}}
+static inline int si_forward() {} // expected-warning{{non-void function does not return a value}}
 
 // Test warnings on ignored qualifiers on return types.
 const int ignored_c_quals(); // expected-warning{{'const' type qualifier on return type has no effect}}
@@ -319,7 +319,7 @@
   default:
     break;
   }
-} // expected-warning {{control may reach end of non-void function}}
+} // expected-warning {{non-void function does not return a value in all control paths}}
 
 // sizeof(long) test.
 int sizeof_long() {
@@ -338,4 +338,4 @@
     });
   else
     return 0;
-} // no-warning (used to be "control may reach end of non-void function")
+} // no-warning (used to be "non-void function does not return a value in all control paths")
diff --git a/clang/test/SemaCXX/attr-noreturn.cpp b/clang/test/SemaCXX/attr-noreturn.cpp
--- a/clang/test/SemaCXX/attr-noreturn.cpp
+++ b/clang/test/SemaCXX/attr-noreturn.cpp
@@ -10,7 +10,7 @@
 
   int &test1() {
     a.nofail();
-  } // expected-warning {{control reaches end of non-void function}}
+  } // expected-warning {{non-void function does not return a value}}
 
   int &test2() {
     a.fail();
diff --git a/clang/test/SemaCXX/coreturn.cpp b/clang/test/SemaCXX/coreturn.cpp
--- a/clang/test/SemaCXX/coreturn.cpp
+++ b/clang/test/SemaCXX/coreturn.cpp
@@ -88,12 +88,12 @@
 
 int test2() {
   co_await a;
-} // expected-warning {{control reaches end of coroutine; which is undefined behavior because the promise type 'std::experimental::coroutine_traits<int>::promise_type' (aka 'promise_int') does not declare 'return_void()'}}
+} // expected-warning {{non-void coroutine does not return a value}}
 
 int test2a(bool b) {
   if (b)
     co_return 42;
-} // expected-warning {{control may reach end of coroutine; which is undefined behavior because the promise type 'std::experimental::coroutine_traits<int, bool>::promise_type' (aka 'promise_int') does not declare 'return_void()'}}
+} // expected-warning {{non-void coroutine does not return a value in all control paths}}
 
 int test3() {
   co_await a;
@@ -107,12 +107,12 @@
 
 void test5(int) {
   co_await a;
-} // expected-warning {{control reaches end of coroutine; which is undefined behavior because}}
+} // expected-warning {{non-void coroutine does not return a value}}
 
 void test6(int x) {
   if (x)
     co_return 42;
-} // expected-warning {{control may reach end of coroutine; which is undefined behavior because}}
+} // expected-warning {{non-void coroutine does not return a value in all control paths}}
 
 void test7(int y) {
   if (y)
@@ -132,9 +132,9 @@
 
 VoidTagReturnValue test10() {
   co_await a;
-} // expected-warning {{control reaches end of coroutine}}
+} // expected-warning {{non-void coroutine does not return a value}}
 
 VoidTagReturnValue test11(bool b) {
   if (b)
     co_return 42;
-} // expected-warning {{control may reach end of coroutine}}
+} // expected-warning {{non-void coroutine does not return a value in all control paths}}
diff --git a/clang/test/SemaCXX/return-noreturn.cpp b/clang/test/SemaCXX/return-noreturn.cpp
--- a/clang/test/SemaCXX/return-noreturn.cpp
+++ b/clang/test/SemaCXX/return-noreturn.cpp
@@ -26,7 +26,7 @@
   }
   int f2_positive(int x) {
     switch (x) { default: ; }
-  } // expected-warning {{control reaches end of non-void function}}
+  } // expected-warning {{non-void function does not return a value}}
   int f3(int x) {
     switch (x) { default: { pr6884_abort_struct(); } }
   }
@@ -46,7 +46,7 @@
       pr6884_abort_struct *p = new pr6884_abort_struct();
       delete p;
     }
-  } // expected-warning {{control reaches end of non-void function}}
+  } // expected-warning {{non-void function does not return a value}}
 
   // Test that these constructs work even when extraneous blocks are created
   // before and after the switch due to implicit destructors.
@@ -61,7 +61,7 @@
   int g2_positive(int x) {
     other o;
     switch (x) { default: ; }
-  } // expected-warning {{control reaches end of non-void function}}
+  } // expected-warning {{non-void function does not return a value}}
   int g3(int x) {
     other o;
     switch (x) { default: { pr6884_abort_struct(); } }
@@ -140,7 +140,7 @@
     default:
         break;
   }
-} // expected-warning {{control reaches end of non-void function}}
+} // expected-warning {{non-void function does not return a value}}
 
 void PR9412_f() {
     PR9412_t<PR9412_Exact>(); // expected-note {{in instantiation of function template specialization 'PR9412_t<PR9412_Exact>' requested here}}
@@ -165,7 +165,7 @@
 
 int testTernaryStaticallyConditionalRetrunOnTrue() {
   true ? Return() : NoReturn();
-} // expected-warning {{control reaches end of non-void function}}
+} // expected-warning {{non-void function does not return a value}}
 
 int testTernaryStaticallyConditionalNoretrunOnFalse() {
   false ? Return() : NoReturn();
@@ -173,23 +173,23 @@
 
 int testTernaryStaticallyConditionalRetrunOnFalse() {
   false ? NoReturn() : Return();
-} // expected-warning {{control reaches end of non-void function}}
+} // expected-warning {{non-void function does not return a value}}
 
 int testTernaryConditionalNoreturnTrueBranch(bool value) {
   value ? (NoReturn() || NoReturn()) : Return();
-} // expected-warning {{control may reach end of non-void function}}
+} // expected-warning {{non-void function does not return a value in all control paths}}
 
 int testTernaryConditionalNoreturnFalseBranch(bool value) {
   value ? Return() : (NoReturn() || NoReturn());
-} // expected-warning {{control may reach end of non-void function}}
+} // expected-warning {{non-void function does not return a value in all control paths}}
 
 int testConditionallyExecutedComplexTernaryTrueBranch(bool value) {
   value || (true ? NoReturn() : true);
-} // expected-warning {{control may reach end of non-void function}}
+} // expected-warning {{non-void function does not return a value in all control paths}}
 
 int testConditionallyExecutedComplexTernaryFalseBranch(bool value) {
   value || (false ? true : NoReturn());
-} // expected-warning {{control may reach end of non-void function}}
+} // expected-warning {{non-void function does not return a value in all control paths}}
 
 int testStaticallyExecutedLogicalOrBranch() {
   false || NoReturn();
@@ -201,19 +201,19 @@
 
 int testStaticallySkippedLogicalOrBranch() {
   true || NoReturn();
-} // expected-warning {{control reaches end of non-void function}}
+} // expected-warning {{non-void function does not return a value}}
 
 int testStaticallySkppedLogicalAndBranch() {
   false && NoReturn();
-} // expected-warning {{control reaches end of non-void function}}
+} // expected-warning {{non-void function does not return a value}}
 
 int testConditionallyExecutedComplexLogicalBranch(bool value) {
   value || (true && NoReturn());
-} // expected-warning {{control may reach end of non-void function}}
+} // expected-warning {{non-void function does not return a value in all control paths}}
 
 int testConditionallyExecutedComplexLogicalBranch2(bool value) {
   (true && value) || (true && NoReturn());
-} // expected-warning {{control may reach end of non-void function}}
+} // expected-warning {{non-void function does not return a value in all control paths}}
 
 int testConditionallyExecutedComplexLogicalBranch3(bool value) {
   (false && (Return() || true)) || (true && NoReturn());
@@ -236,7 +236,7 @@
   int bar() {
     X work([](){ Fatal(); });
     foo();
-  } // expected-warning {{control reaches end of non-void function}}
+  } // expected-warning {{non-void function does not return a value}}
 
   int baz() {
     FatalCopy fc;
@@ -250,12 +250,12 @@
 int functionTryBlock1(int s) try {
   return 0;
 } catch (...) {
-} // expected-warning {{control may reach end of non-void function}}
+} // expected-warning {{non-void function does not return a value in all control paths}}
 
 int functionTryBlock2(int s) try {
 } catch (...) {
   return 0;
-} // expected-warning {{control may reach end of non-void function}}
+} // expected-warning {{non-void function does not return a value in all control paths}}
 
 int functionTryBlock3(int s) try {
   return 0;
diff --git a/clang/test/SemaCXX/warn-missing-noreturn.cpp b/clang/test/SemaCXX/warn-missing-noreturn.cpp
--- a/clang/test/SemaCXX/warn-missing-noreturn.cpp
+++ b/clang/test/SemaCXX/warn-missing-noreturn.cpp
@@ -91,7 +91,7 @@
 
 int rdar8875247_test() {
   rdar8875247 f;
-} // expected-warning{{control reaches end of non-void function}}
+} // expected-warning{{non-void function does not return a value}}
 
 struct rdar8875247_B {
   rdar8875247_B();
diff --git a/clang/test/SemaTemplate/late-parsing-eager-instantiation.cpp b/clang/test/SemaTemplate/late-parsing-eager-instantiation.cpp
--- a/clang/test/SemaTemplate/late-parsing-eager-instantiation.cpp
+++ b/clang/test/SemaTemplate/late-parsing-eager-instantiation.cpp
@@ -15,8 +15,8 @@
   char data() {
     visit([](auto buffer) -> char { // expected-note {{in instantiation}}
       buffer->data();
-    }); // expected-warning {{control reaches end of non-void lambda}}
-  } // expected-warning {{control reaches end of non-void function}}
+    }); // expected-warning {{non-void lambda does not return a value}}
+  } // expected-warning {{non-void function does not return a value}}
 };
 
 // pr34185