Index: include/clang/Basic/Attr.td
===================================================================
--- include/clang/Basic/Attr.td
+++ include/clang/Basic/Attr.td
@@ -1431,7 +1431,8 @@
 
 def NoThrow : InheritableAttr {
   let Spellings = [GCC<"nothrow">, Declspec<"nothrow">];
-  let Documentation = [Undocumented];
+  let Subjects = SubjectList<[Function]>;
+  let Documentation = [NoThrowDocs];
 }
 
 def NvWeak : IgnoredAttr {
Index: include/clang/Basic/AttrDocs.td
===================================================================
--- include/clang/Basic/AttrDocs.td
+++ include/clang/Basic/AttrDocs.td
@@ -2686,6 +2686,17 @@
   }];
 }
 
+def NoThrowDocs : Documentation {
+  let Category = DocCatFunction;
+  let Content = [{
+Clang supports the GNU style ``__attribute__((nothrow))`` attribute as an
+equivilent of `noexcept` on function declarations. This attribute informs the
+compiler that the annotated function does cannot throw an exception. This
+prevents exception-unwinding. This attribute is particularly useful on functions
+in the C Standard Library that are guaranteed to not throw an exception.
+    }];
+}
+
 def InternalLinkageDocs : Documentation {
   let Category = DocCatFunction;
   let Content = [{
Index: test/Misc/pragma-attribute-supported-attributes-list.test
===================================================================
--- test/Misc/pragma-attribute-supported-attributes-list.test
+++ test/Misc/pragma-attribute-supported-attributes-list.test
@@ -2,7 +2,7 @@
 
 // The number of supported attributes should never go down!
 
-// CHECK: #pragma clang attribute supports 64 attributes:
+// CHECK: #pragma clang attribute supports 65 attributes:
 // CHECK-NEXT: AMDGPUFlatWorkGroupSize (SubjectMatchRule_function)
 // CHECK-NEXT: AMDGPUNumSGPR (SubjectMatchRule_function)
 // CHECK-NEXT: AMDGPUNumVGPR (SubjectMatchRule_function)
@@ -39,6 +39,7 @@
 // CHECK-NEXT: NoSanitize (SubjectMatchRule_function, SubjectMatchRule_objc_method, SubjectMatchRule_variable_is_global)
 // CHECK-NEXT: NoSanitizeSpecific (SubjectMatchRule_function, SubjectMatchRule_variable_is_global)
 // CHECK-NEXT: NoSplitStack (SubjectMatchRule_function)
+// CHECK-NEXT: NoThrow (SubjectMatchRule_function)
 // CHECK-NEXT: NotTailCalled (SubjectMatchRule_function)
 // CHECK-NEXT: ObjCBoxable (SubjectMatchRule_record)
 // CHECK-NEXT: ObjCMethodFamily (SubjectMatchRule_objc_method)