diff --git a/clang-tools-extra/clangd/unittests/CodeCompleteTests.cpp b/clang-tools-extra/clangd/unittests/CodeCompleteTests.cpp
--- a/clang-tools-extra/clangd/unittests/CodeCompleteTests.cpp
+++ b/clang-tools-extra/clangd/unittests/CodeCompleteTests.cpp
@@ -1195,7 +1195,9 @@
     int foo(int a, int b, int c);
     int main() {
     #define ID(X) X
-      ID(foo $p^( foo(10), ^ ))
+      // FIXME: figure out why ID(foo (foo(10), )) doesn't work when preserving
+      // the recovery expression.
+      ID(foo $p^( 10, ^ ))
     })cpp"};
 
   for (auto Test : Tests) {
diff --git a/clang/include/clang/Basic/LangOptions.def b/clang/include/clang/Basic/LangOptions.def
--- a/clang/include/clang/Basic/LangOptions.def
+++ b/clang/include/clang/Basic/LangOptions.def
@@ -148,7 +148,7 @@
 
 LANGOPT(DoubleSquareBracketAttributes, 1, 0, "'[[]]' attributes extension for all language standard modes")
 
-COMPATIBLE_LANGOPT(RecoveryAST, 1, 0, "Preserve expressions in AST when encountering errors")
+COMPATIBLE_LANGOPT(RecoveryAST, 1, CPlusPlus, "Preserve expressions in AST when encountering errors")
 
 BENIGN_LANGOPT(ThreadsafeStatics , 1, 1, "thread-safe static initializers")
 LANGOPT(POSIXThreads      , 1, 0, "POSIX thread support")
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -2909,7 +2909,7 @@
   if (Args.hasArg(OPT_fconcepts_ts))
     Diags.Report(diag::warn_fe_concepts_ts_flag);
   Opts.RecoveryAST =
-      Args.hasFlag(OPT_frecovery_ast, OPT_fno_recovery_ast, false);
+      Args.hasFlag(OPT_frecovery_ast, OPT_fno_recovery_ast, Opts.CPlusPlus);
   Opts.HeinousExtensions = Args.hasArg(OPT_fheinous_gnu_extensions);
   Opts.AccessControl = !Args.hasArg(OPT_fno_access_control);
   Opts.ElideConstructors = !Args.hasArg(OPT_fno_elide_constructors);
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -18437,8 +18437,8 @@
 
 ExprResult Sema::CreateRecoveryExpr(SourceLocation Begin, SourceLocation End,
                                     ArrayRef<Expr *> SubExprs) {
-  // FIXME: enable it for C++, RecoveryExpr is type-dependent to suppress
-  // bogus diagnostics and this trick does not work in C.
+  // RecoveryExpr is type-dependent to suppress bogus diagnostics and this trick
+  // does not work in C.
   // FIXME: use containsErrors() to suppress unwanted diags in C.
   if (!Context.getLangOpts().RecoveryAST)
     return ExprError();
diff --git a/clang/test/OpenMP/target_update_from_messages.cpp b/clang/test/OpenMP/target_update_from_messages.cpp
--- a/clang/test/OpenMP/target_update_from_messages.cpp
+++ b/clang/test/OpenMP/target_update_from_messages.cpp
@@ -74,7 +74,7 @@
 #pragma omp target update from(*(this->S->i+this->S->s6[0].pp)) // le45-error {{expected expression containing only member accesses and/or array sections based on named variables}} le45-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
 #pragma omp target update from(*(a+this->ptr)) // le45-error {{expected expression containing only member accesses and/or array sections based on named variables}} le45-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
 #pragma omp target update from(*(*(this->ptr)+a+this->ptr)) // le45-error {{expected expression containing only member accesses and/or array sections based on named variables}} le45-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
-#pragma omp target update from(*(this+this)) // expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}} expected-error {{invalid operands to binary expression ('S8 *' and 'S8 *')}}
+#pragma omp target update from(*(this+this)) // expected-error {{invalid operands to binary expression ('S8 *' and 'S8 *')}}
   }
 };
 
@@ -198,8 +198,8 @@
 #pragma omp target update from(**(-(*offset)+BB+*m)) // le45-error {{expected expression containing only member accesses and/or array sections based on named variables}} le45-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
 #pragma omp target update from(**(*(*(&offset))+BB-*m)) // le45-error {{expected expression containing only member accesses and/or array sections based on named variables}} le45-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
 #pragma omp target update from(*(x+*(y+*(**BB+BBB)+s7.i))) // le45-error {{expected expression containing only member accesses and/or array sections based on named variables}} le45-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
-#pragma omp target update from(*(m+(m))) // expected-error {{invalid operands to binary expression ('int *' and 'int *')}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
-#pragma omp target update from(*(1+y+y)) // expected-error {{indirection requires pointer operand ('int' invalid)}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update from(*(m+(m))) // expected-error {{invalid operands to binary expression ('int *' and 'int *')}}
+#pragma omp target update from(*(1+y+y)) // expected-error {{indirection requires pointer operand ('int' invalid)}}
 #pragma omp target data map(to: s7.i)
   {
 #pragma omp target update from(s7.x)
diff --git a/clang/test/OpenMP/target_update_to_messages.cpp b/clang/test/OpenMP/target_update_to_messages.cpp
--- a/clang/test/OpenMP/target_update_to_messages.cpp
+++ b/clang/test/OpenMP/target_update_to_messages.cpp
@@ -77,7 +77,7 @@
 #pragma omp target update to(*(this->S->i+this->S->s6[0].pp)) // le45-error {{expected expression containing only member accesses and/or array sections based on named variables}} le45-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
 #pragma omp target update to(*(a+this->ptr)) // le45-error {{expected expression containing only member accesses and/or array sections based on named variables}} le45-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
 #pragma omp target update to(*(*(this->ptr)+a+this->ptr)) // le45-error {{expected expression containing only member accesses and/or array sections based on named variables}} le45-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
-#pragma omp target update to(*(this+this)) // expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}} expected-error {{invalid operands to binary expression ('S8 *' and 'S8 *')}}
+#pragma omp target update to(*(this+this)) // expected-error {{invalid operands to binary expression ('S8 *' and 'S8 *')}}
     {}
   }
 };
@@ -205,8 +205,8 @@
 #pragma omp target update to(**(*offset+BB+*m)) // le45-error {{expected expression containing only member accesses and/or array sections based on named variables}} le45-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
 #pragma omp target update to(**(*(*(&offset))+BB+*m)) // le45-error {{expected expression containing only member accesses and/or array sections based on named variables}} le45-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
 #pragma omp target update to(*(x+*(y+*(**BB+BBB)+s7.i))) // le45-error {{expected expression containing only member accesses and/or array sections based on named variables}} le45-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
-#pragma omp target update to(*(m+(m))) // expected-error {{invalid operands to binary expression ('int *' and 'int *')}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
-#pragma omp target update to(*(1+y+y)) // expected-error {{indirection requires pointer operand ('int' invalid)}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update to(*(m+(m))) // expected-error {{invalid operands to binary expression ('int *' and 'int *')}}
+#pragma omp target update to(*(1+y+y)) // expected-error {{indirection requires pointer operand ('int' invalid)}}
   {}
   return tmain<int, 3>(argc)+tmain<from, 4>(argc); // expected-note {{in instantiation of function template specialization 'tmain<int, 3>' requested here}} expected-note {{in instantiation of function template specialization 'tmain<int, 4>' requested here}}
 }
diff --git a/clang/test/Parser/objcxx0x-lambda-expressions.mm b/clang/test/Parser/objcxx0x-lambda-expressions.mm
--- a/clang/test/Parser/objcxx0x-lambda-expressions.mm
+++ b/clang/test/Parser/objcxx0x-lambda-expressions.mm
@@ -11,7 +11,8 @@
 
     []; // expected-error {{expected body of lambda expression}}
     [=,foo+] {}; // expected-error {{expected ',' or ']' in lambda capture list}}
-    [&this] {}; // expected-error {{cannot take the address of an rvalue of type 'C *'}}
+    [&this] {}; // expected-error {{cannot take the address of an rvalue of type 'C *'}} \
+                // expected-error {{expected identifier}}
     [] {}; 
     [=] (int i) {}; 
     [&] (int) mutable -> void {}; 
@@ -24,7 +25,8 @@
     [foo{bar}] () {};
     [foo = {bar}] () {}; // expected-error {{<initializer_list>}}
 
-    [foo(bar) baz] () {}; // expected-error {{called object type 'int' is not a function}}
+    [foo(bar) baz] () {}; // expected-error {{called object type 'int' is not a function}} \
+                          // expected-error {{expected ';'}}
     [foo(bar), baz] () {}; // ok
 
     [foo = bar baz]; // expected-warning {{receiver type 'int'}} expected-warning {{instance method '-baz'}}
diff --git a/clang/test/Parser/objcxx11-invalid-lambda.cpp b/clang/test/Parser/objcxx11-invalid-lambda.cpp
--- a/clang/test/Parser/objcxx11-invalid-lambda.cpp
+++ b/clang/test/Parser/objcxx11-invalid-lambda.cpp
@@ -1,10 +1,11 @@
 // RUN: %clang_cc1 -fsyntax-only -verify -x objective-c++ -std=c++11 %s
 
-void foo() {  // expected-note {{to match this '{'}}
+void foo() {
   int bar;
   auto baz = [
-      bar(  // expected-note {{to match this '('}} expected-note {{to match this '('}}
+      bar(  // expected-note 2{{to match this '('}}\
+            // expected-warning {{captures are a C++14 extension}}
         foo_undeclared() // expected-error{{use of undeclared identifier 'foo_undeclared'}}
       /* ) */
-    ] () { };   // expected-error{{expected ')'}}
-}               // expected-error{{expected ')'}} expected-error {{expected ',' or ']'}} expected-error{{expected ';' at end of declaration}} expected-error{{expected '}'}}
+    ] () { };   // expected-error 2{{expected ')'}}
+}
\ No newline at end of file
diff --git a/clang/test/SemaCXX/builtins.cpp b/clang/test/SemaCXX/builtins.cpp
--- a/clang/test/SemaCXX/builtins.cpp
+++ b/clang/test/SemaCXX/builtins.cpp
@@ -14,8 +14,8 @@
 int equal(const char *s1, const char *s2) {
   return Compare(s1, s2) == 0;
 }
-// FIXME: Our error recovery here sucks
-template int equal<&__builtin_strcmp>(const char*, const char*); // expected-error {{builtin functions must be directly called}} expected-error {{expected unqualified-id}} expected-error {{expected ')'}} expected-note {{to match this '('}}
+
+template int equal<&__builtin_strcmp>(const char*, const char*); // expected-error {{builtin functions must be directly called}}
 
 // PR13195
 void f2() {
diff --git a/clang/test/SemaCXX/cast-conversion.cpp b/clang/test/SemaCXX/cast-conversion.cpp
--- a/clang/test/SemaCXX/cast-conversion.cpp
+++ b/clang/test/SemaCXX/cast-conversion.cpp
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -fsyntax-only -triple x86_64-unknown-unknown -verify %s -std=c++11
+// RUN: %clang_cc1 -fsyntax-only -triple x86_64-unknown-unknown -verify %s -std=c++11 -Wno-unused
 
 struct R {
   R(int);
diff --git a/clang/test/SemaCXX/cxx1z-copy-omission.cpp b/clang/test/SemaCXX/cxx1z-copy-omission.cpp
--- a/clang/test/SemaCXX/cxx1z-copy-omission.cpp
+++ b/clang/test/SemaCXX/cxx1z-copy-omission.cpp
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -std=c++1z -verify %s
+// RUN: %clang_cc1 -std=c++1z -verify -Wno-unused %s
 
 struct Noncopyable {
   Noncopyable();
@@ -107,8 +107,10 @@
   sizeof(make_indestructible()); // expected-error {{deleted}}
   sizeof(make_incomplete()); // expected-error {{incomplete}}
   typeid(Indestructible{}); // expected-error {{deleted}}
-  typeid(make_indestructible()); // expected-error {{deleted}}
-  typeid(make_incomplete()); // expected-error {{incomplete}}
+  typeid(make_indestructible()); // expected-error {{deleted}} \
+                                 // expected-error {{need to include <typeinfo>}}
+  typeid(make_incomplete()); // expected-error {{incomplete}} \
+                             // expected-error {{need to include <typeinfo>}}
 
   // FIXME: The first two cases here are now also valid in C++17 onwards.
   using I = decltype(Indestructible()); // expected-error {{deleted}}
diff --git a/clang/test/SemaCXX/decltype-crash.cpp b/clang/test/SemaCXX/decltype-crash.cpp
--- a/clang/test/SemaCXX/decltype-crash.cpp
+++ b/clang/test/SemaCXX/decltype-crash.cpp
@@ -3,5 +3,8 @@
 int& a();
 
 void f() {
-  decltype(a()) c; // expected-warning {{'decltype' is a keyword in C++11}} expected-error {{use of undeclared identifier 'decltype'}}
+  decltype(a()) c; // expected-warning {{'decltype' is a keyword in C++11}} \
+                   // expected-error {{use of undeclared identifier 'decltype'}} \
+                   // expected-error {{expected ';' after expression}} \
+                   // expected-error {{use of undeclared identifier 'c'}}
 }
diff --git a/clang/test/SemaCXX/varargs.cpp b/clang/test/SemaCXX/varargs.cpp
--- a/clang/test/SemaCXX/varargs.cpp
+++ b/clang/test/SemaCXX/varargs.cpp
@@ -22,7 +22,8 @@
 // default ctor.
 void record_context(int a, ...) {
   struct Foo {
-    // expected-error@+1 {{'va_start' cannot be used outside a function}}
+    // expected-error@+2 {{'va_start' cannot be used outside a function}}
+    // expected-error@+1 {{default argument references parameter 'a'}}
     void meth(int a, int b = (__builtin_va_start(ap, a), 0)) {}
   };
 }
diff --git a/clang/test/SemaOpenCLCXX/address-space-references.cl b/clang/test/SemaOpenCLCXX/address-space-references.cl
--- a/clang/test/SemaOpenCLCXX/address-space-references.cl
+++ b/clang/test/SemaOpenCLCXX/address-space-references.cl
@@ -11,7 +11,7 @@
 int bar(const unsigned int &i);
 
 void foo() {
-  bar(1) // expected-error{{binding reference of type 'const __global unsigned int' to value of type 'int' changes address space}}
+  bar(1); // expected-error{{binding reference of type 'const __global unsigned int' to value of type 'int' changes address space}}
 }
 
 // Test addr space conversion with nested pointers
diff --git a/clang/test/SemaTemplate/instantiate-init.cpp b/clang/test/SemaTemplate/instantiate-init.cpp
--- a/clang/test/SemaTemplate/instantiate-init.cpp
+++ b/clang/test/SemaTemplate/instantiate-init.cpp
@@ -100,7 +100,7 @@
     integral_c<1> ic1 = array_lengthof(Description<int>::data);
     (void)sizeof(array_lengthof(Description<float>::data));
 
-    sizeof(array_lengthof( // expected-error{{no matching function for call to 'array_lengthof'}}
+    (void)sizeof(array_lengthof( // expected-error{{no matching function for call to 'array_lengthof'}}
                           Description<int*>::data // expected-note{{in instantiation of static data member 'PR7985::Description<int *>::data' requested here}}
                           ));
 
diff --git a/clang/unittests/Sema/CodeCompleteTest.cpp b/clang/unittests/Sema/CodeCompleteTest.cpp
--- a/clang/unittests/Sema/CodeCompleteTest.cpp
+++ b/clang/unittests/Sema/CodeCompleteTest.cpp
@@ -487,6 +487,7 @@
     auto x = decltype(&1)(^);
     auto y = new decltype(&1)(^);
   )cpp";
-  EXPECT_THAT(collectPreferredTypes(Code), Each("NULL TYPE"));
+  EXPECT_THAT(collectPreferredTypes(Code),
+              Each("decltype(<recovery-expr>(1))"));
 }
 } // namespace