Index: include/clang/Basic/Attr.td
===================================================================
--- include/clang/Basic/Attr.td
+++ include/clang/Basic/Attr.td
@@ -2029,6 +2029,12 @@
 
 // Microsoft-related attributes
 
+def MSHookPrologue : InheritableAttr {
+  let Spellings = [GCC<"ms_hook_prologue">];
+  let Subjects = SubjectList<[Function]>;
+  let Documentation = [MSHookPrologueDocs];
+}
+
 def MSNoVTable : InheritableAttr, TargetSpecificAttr<TargetMicrosoftCXXABI> {
   let Spellings = [Declspec<"novtable">];
   let Subjects = SubjectList<[CXXRecord]>;
Index: include/clang/Basic/AttrDocs.td
===================================================================
--- include/clang/Basic/AttrDocs.td
+++ include/clang/Basic/AttrDocs.td
@@ -494,6 +494,19 @@
   }];
 }
 
+def MSHookPrologueDocs : Documentation {
+  let Category = DocCatFunction;
+  let Content = [{
+The ``ms_hook_prologue`` attribute marks a function as "hotpatchable" according
+to conventions used on Windows. Specifically, enough space will be ensured
+in the prologue for a short jump, and an architecturally dependently sized
+patch space will be reserved prior to the entry point. See the documentation
+for the `/HOTPATCH`_ switch on MSDN.
+
+.. _`/HOTPATCH/: https://msdn.microsoft.com/en-us/library/ms173507.aspx
+  }];
+}
+
 def NoDebugDocs : Documentation {
   let Category = DocCatVariable;
   let Content = [{
Index: lib/CodeGen/TargetInfo.cpp
===================================================================
--- lib/CodeGen/TargetInfo.cpp
+++ lib/CodeGen/TargetInfo.cpp
@@ -1749,6 +1749,10 @@
       llvm::Function *Fn = cast<llvm::Function>(GV);
       Fn->setCallingConv(llvm::CallingConv::X86_INTR);
     }
+    if (FD->hasAttr<MSHookPrologueAttr>()) {
+      llvm::Function *Fn = cast<llvm::Function>(GV);
+      Fn->addFnAttr("patchable-function", "ms-hotpatch");
+    }
   }
 }
 
@@ -2079,6 +2083,10 @@
         llvm::Function *Fn = cast<llvm::Function>(GV);
         Fn->setCallingConv(llvm::CallingConv::X86_INTR);
       }
+      if (FD->hasAttr<MSHookPrologueAttr>()) {
+        llvm::Function *Fn = cast<llvm::Function>(GV);
+        Fn->addFnAttr("patchable-function", "ms-hotpatch");
+      }
     }
   }
 };
Index: lib/Sema/SemaDeclAttr.cpp
===================================================================
--- lib/Sema/SemaDeclAttr.cpp
+++ lib/Sema/SemaDeclAttr.cpp
@@ -5748,6 +5748,9 @@
     break;
 
   // Microsoft attributes:
+  case AttributeList::AT_MSHookPrologue:
+    handleSimpleAttribute<MSHookPrologueAttr>(S, D, Attr);
+    break;
   case AttributeList::AT_MSNoVTable:
     handleSimpleAttribute<MSNoVTableAttr>(S, D, Attr);
     break;
Index: test/CodeGen/function-attributes.c
===================================================================
--- test/CodeGen/function-attributes.c
+++ test/CodeGen/function-attributes.c
@@ -108,11 +108,18 @@
   _setjmp(0);
 }
 
+// CHECK-LABEL: define void @f21
+// CHECK: [[HOTPATCH:#[0-9]+]]
+// CHECK: {
+void __attribute__((ms_hook_prologue)) f21(void) {
+}
+
 // CHECK: attributes [[NUW]] = { nounwind optsize{{.*}} }
 // CHECK: attributes [[AI]] = { alwaysinline nounwind optsize{{.*}} }
 // CHECK: attributes [[NUW_OS_RN]] = { nounwind optsize readnone{{.*}} }
 // CHECK: attributes [[ALIGN]] = { nounwind optsize alignstack=16{{.*}} }
 // CHECK: attributes [[RT]] = { nounwind optsize returns_twice{{.*}} }
+// CHECK: attributes [[HOTPATCH]] = { nounwind optsize{{.*}}"patchable-function"="ms-hotpatch"{{.*}} }
 // CHECK: attributes [[NR]] = { noreturn optsize }
 // CHECK: attributes [[NUW_RN]] = { nounwind optsize readnone }
 // CHECK: attributes [[RT_CALL]] = { optsize returns_twice }