Index: cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
+++ cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
@@ -2966,6 +2966,7 @@
   "|on builtin function"
   "}1">,
   InGroup<IgnoredAttributes>;
+def error_cconv_unsupported : Error<warn_cconv_unsupported.Text>;
 def err_cconv_knr : Error<
   "function with no prototype cannot use the %0 calling convention">;
 def warn_cconv_knr : Warning<
Index: cfe/trunk/include/clang/Basic/TargetInfo.h
===================================================================
--- cfe/trunk/include/clang/Basic/TargetInfo.h
+++ cfe/trunk/include/clang/Basic/TargetInfo.h
@@ -1268,6 +1268,7 @@
     CCCR_OK,
     CCCR_Warning,
     CCCR_Ignore,
+    CCCR_Error,
   };
 
   /// Determines whether a given calling convention is valid for the
Index: cfe/trunk/lib/Basic/Targets/OSTargets.h
===================================================================
--- cfe/trunk/lib/Basic/Targets/OSTargets.h
+++ cfe/trunk/lib/Basic/Targets/OSTargets.h
@@ -561,6 +561,10 @@
       break;
     }
   }
+  TargetInfo::CallingConvCheckResult
+  checkCallingConvention(CallingConv CC) const override {
+    return (CC == CC_C) ? TargetInfo::CCCR_OK : TargetInfo::CCCR_Error;
+  }
 };
 
 // RTEMS Target
Index: cfe/trunk/lib/Sema/SemaDeclAttr.cpp
===================================================================
--- cfe/trunk/lib/Sema/SemaDeclAttr.cpp
+++ cfe/trunk/lib/Sema/SemaDeclAttr.cpp
@@ -4668,6 +4668,11 @@
     CC = CC_C;
     break;
 
+  case TargetInfo::CCCR_Error:
+    Diag(Attrs.getLoc(), diag::error_cconv_unsupported)
+        << Attrs << (int)CallingConventionIgnoredReason::ForThisTarget;
+    break;
+
   case TargetInfo::CCCR_Warning: {
     Diag(Attrs.getLoc(), diag::warn_cconv_unsupported)
         << Attrs << (int)CallingConventionIgnoredReason::ForThisTarget;
Index: cfe/trunk/test/Sema/no_callconv.cpp
===================================================================
--- cfe/trunk/test/Sema/no_callconv.cpp
+++ cfe/trunk/test/Sema/no_callconv.cpp
@@ -0,0 +1,44 @@
+// RUN: %clang_cc1 %s -triple x86_64-scei-ps4 -DPS4 -fsyntax-only -verify
+// RUN: %clang_cc1 %s -triple x86_64-unknown-linux-gnu -fsyntax-only -verify
+
+#ifdef PS4
+
+// PS4 does not support these.
+void __vectorcall func_vc() {} // expected-error {{'__vectorcall' calling convention is not supported for this target}}
+void __regcall func_rc() {} // expected-error {{'__regcall' calling convention is not supported for this target}}
+void __attribute__((vectorcall)) funcA() {} // expected-error {{'vectorcall' calling convention is not supported for this target}}
+void __attribute__((regcall)) funcB() {} // expected-error {{'regcall' calling convention is not supported for this target}}
+void __attribute__((ms_abi)) funcH() {} // expected-error {{'ms_abi' calling convention is not supported for this target}}
+void __attribute__((intel_ocl_bicc)) funcJ() {} // expected-error {{'intel_ocl_bicc' calling convention is not supported for this target}}
+void __attribute__((swiftcall)) funcK() {} // expected-error {{'swiftcall' calling convention is not supported for this target}}
+void __attribute__((pascal)) funcG() {} // expected-error {{'pascal' calling convention is not supported for this target}}
+void __attribute__((preserve_most)) funcL() {} // expected-error {{'preserve_most' calling convention is not supported for this target}}
+void __attribute__((preserve_all)) funcM() {} // expected-error {{'preserve_all' calling convention is not supported for this target}}
+void __attribute__((stdcall)) funcD() {} // expected-error {{'stdcall' calling convention is not supported for this target}}
+void __attribute__((fastcall)) funcE() {} // expected-error {{'fastcall' calling convention is not supported for this target}}
+void __attribute__((thiscall)) funcF() {} // expected-error {{'thiscall' calling convention is not supported for this target}}
+#else
+
+void __vectorcall func_vc() {}
+void __regcall func_rc() {}
+void __attribute__((vectorcall)) funcA() {}
+void __attribute__((regcall)) funcB() {}
+void __attribute__((ms_abi)) funcH() {}
+void __attribute__((intel_ocl_bicc)) funcJ() {}
+void __attribute__((swiftcall)) funcK() {}
+void __attribute__((preserve_most)) funcL() {}
+void __attribute__((preserve_all)) funcM() {}
+
+// Same function with different calling conventions. Error with a note pointing to the last decl.
+void __attribute__((preserve_all)) funcR(); // expected-note {{previous declaration is here}}
+void __attribute__((preserve_most)) funcR(); // expected-error {{function declared 'preserve_most' here was previously declared 'preserve_all'}}
+
+void __attribute__((pascal)) funcG() {} // expected-warning {{'pascal' calling convention is not supported for this target}}
+
+void __attribute__((stdcall)) funcD() {} // expected-warning {{'stdcall' calling convention is not supported for this target}}
+void __attribute__((fastcall)) funcE() {} // expected-warning {{'fastcall' calling convention is not supported for this target}}
+void __attribute__((thiscall)) funcF() {} // expected-warning {{'thiscall' calling convention is not supported for this target}}
+#endif
+
+void __attribute__((sysv_abi)) funcI() {}
+void __attribute__((cdecl)) funcC() {}
Index: cfe/trunk/unittests/Tooling/RecursiveASTVisitorTests/LambdaExpr.cpp
===================================================================
--- cfe/trunk/unittests/Tooling/RecursiveASTVisitorTests/LambdaExpr.cpp
+++ cfe/trunk/unittests/Tooling/RecursiveASTVisitorTests/LambdaExpr.cpp
@@ -86,6 +86,8 @@
 }
 
 TEST(RecursiveASTVisitor, VisitsAttributedLambdaExpr) {
+  if (llvm::Triple(llvm::sys::getDefaultTargetTriple()).isPS4())
+    return; // PS4 does not support fastcall.
   LambdaExprVisitor Visitor;
   Visitor.ExpectMatch("", 1, 12);
   EXPECT_TRUE(Visitor.runOver(