diff --git a/clang/include/clang/Basic/Attr.td b/clang/include/clang/Basic/Attr.td
--- a/clang/include/clang/Basic/Attr.td
+++ b/clang/include/clang/Basic/Attr.td
@@ -2216,6 +2216,12 @@
   let Documentation = [SuppressDocs];
 }
 
+def HardenMisspeculation : StmtAttr {
+  let Spellings = [Clang<"harden_misspeculation">];
+  let Args = [VariadicIdentifierArgument<"VariablesToHarden">];
+  let Documentation = [HardenMisspeculationDocs];
+}
+
 def SysVABI : DeclOrTypeAttr {
   let Spellings = [GCC<"sysv_abi">];
 //  let Subjects = [Function, ObjCMethod];
diff --git a/clang/include/clang/Basic/AttrDocs.td b/clang/include/clang/Basic/AttrDocs.td
--- a/clang/include/clang/Basic/AttrDocs.td
+++ b/clang/include/clang/Basic/AttrDocs.td
@@ -3873,6 +3873,13 @@
   }];
 }
 
+def HardenMisspeculationDocs : Documentation {
+  let Category = DocCatStmt;
+  let Content = [{
+TODO(zbrid): Add documentation
+  }];
+}
+
 def AbiTagsDocs : Documentation {
   let Category = DocCatFunction;
   let Content = [{
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
@@ -9155,6 +9155,10 @@
   "fallthrough annotation in unreachable code">,
   InGroup<ImplicitFallthrough>, DefaultIgnore;
 
+def err_harden_misspeculation_attr_wrong_target
+    : Error<"%0 attribute is only allowed on compound statements (ie block "
+            "statements)">;
+
 def warn_unreachable_default : Warning<
   "default label in switch which covers all enumeration values">,
   InGroup<CoveredSwitchDefault>, DefaultIgnore;
diff --git a/clang/lib/Sema/SemaStmtAttr.cpp b/clang/lib/Sema/SemaStmtAttr.cpp
--- a/clang/lib/Sema/SemaStmtAttr.cpp
+++ b/clang/lib/Sema/SemaStmtAttr.cpp
@@ -10,14 +10,16 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "clang/AST/EvaluatedExprVisitor.h"
-#include "clang/Sema/SemaInternal.h"
 #include "clang/AST/ASTContext.h"
+#include "clang/AST/EvaluatedExprVisitor.h"
 #include "clang/Basic/SourceManager.h"
+#include "clang/Basic/TargetInfo.h"
 #include "clang/Sema/DelayedDiagnostic.h"
 #include "clang/Sema/Lookup.h"
 #include "clang/Sema/ScopeInfo.h"
+#include "clang/Sema/SemaInternal.h"
 #include "llvm/ADT/StringExtras.h"
+#include "llvm/ADT/Triple.h"
 
 using namespace clang;
 using namespace sema;
@@ -51,6 +53,38 @@
   return ::new (S.Context) FallThroughAttr(S.Context, A);
 }
 
+static Attr *handleHardenMisspeculationAttr(Sema &S, Stmt *St,
+                                            const ParsedAttr &A,
+                                            SourceRange Range) {
+  if (!isa<CompoundStmt>(St)) {
+    S.Diag(A.getRange().getBegin(),
+           diag::err_harden_misspeculation_attr_wrong_target)
+        << A << St->getBeginLoc();
+  }
+
+  // FIXME: Support non-x86_64 targets
+  if (!(S.Context.getTargetInfo().getTriple().getArch() ==
+        llvm::Triple::ArchType::x86_64)) {
+    S.Diag(A.getLoc(), diag::err_attribute_unsupported) << A;
+    return nullptr;
+  }
+
+  if (A.getNumArgs() < 1) {
+    S.Diag(A.getLoc(), diag::err_attribute_too_few_arguments) << A << 1;
+    return nullptr;
+  }
+
+  for (unsigned I = 0, E = A.getNumArgs(); I != E; ++I) {
+    if (!A.isArgIdent(I)) {
+      S.Diag(A.getLoc(), diag::err_attribute_argument_type)
+          << A << AANT_ArgumentIdentifier;
+      return nullptr;
+    }
+  }
+
+  return ::new (S.Context) HardenMisspeculationAttr(S.Context, A);
+}
+
 static Attr *handleSuppressAttr(Sema &S, Stmt *St, const ParsedAttr &A,
                                 SourceRange Range) {
   if (A.getNumArgs() < 1) {
@@ -374,6 +408,8 @@
     return handleOpenCLUnrollHint(S, St, A, Range);
   case ParsedAttr::AT_Suppress:
     return handleSuppressAttr(S, St, A, Range);
+  case ParsedAttr::AT_HardenMisspeculation:
+    return handleHardenMisspeculationAttr(S, St, A, Range);
   case ParsedAttr::AT_NoMerge:
     return handleNoMergeAttr(S, St, A, Range);
   default:
diff --git a/clang/test/SemaCXX/attr-harden-misspeculation-unsupported-target.cpp b/clang/test/SemaCXX/attr-harden-misspeculation-unsupported-target.cpp
new file mode 100644
--- /dev/null
+++ b/clang/test/SemaCXX/attr-harden-misspeculation-unsupported-target.cpp
@@ -0,0 +1,9 @@
+// RUN: %clang_cc1 -std=c++11 -triple armv7 -fsyntax-only %s -verify
+
+int b(int a, int b) {
+  if (a < b)
+      [[clang::harden_misspeculation(a)]] { // expected-error {{'harden_misspeculation' attribute is not supported for this target}}
+    return a;
+  }
+  return b;
+}
diff --git a/clang/test/SemaCXX/attr-harden-misspeculation.cpp b/clang/test/SemaCXX/attr-harden-misspeculation.cpp
new file mode 100644
--- /dev/null
+++ b/clang/test/SemaCXX/attr-harden-misspeculation.cpp
@@ -0,0 +1,19 @@
+// RUN: %clang_cc1 -std=c++11 -fsyntax-only %s -verify
+
+int b(int a, int b) {
+  if (a < b)
+      [[clang::harden_misspeculation]] { // expected-error {{'harden_misspeculation' attribute takes at least 1 argument}}
+    a += 2;
+  }
+
+  if (a == b)
+      [[clang::harden_misspeculation(1)]] { // expected-error {{'harden_misspeculation' attribute requires an identifier}}
+    a += 1;
+  }
+
+  if (a > b)
+    [[clang::harden_misspeculation(a)]] // expected-error {{'harden_misspeculation' attribute is only allowed on compound statements (ie block statements)}}
+    return a;
+
+  return a;
+}