diff --git a/clang/include/clang/Analysis/RetainSummaryManager.h b/clang/include/clang/Analysis/RetainSummaryManager.h
--- a/clang/include/clang/Analysis/RetainSummaryManager.h
+++ b/clang/include/clang/Analysis/RetainSummaryManager.h
@@ -495,12 +495,36 @@
   /// effects.
   llvm::FoldingSet<CachedSummaryNode> SimpleSummaries;
 
+  /// Create arg effects to all OS object out parameters.
+  ArgEffects getOSOutParametersMap(const FunctionDecl *FD, ArgEffectKind AEK);
+
+  /// Create +1 arg effects to all OS object out parameters. Takes return type
+  /// into account if it's a kern_return_t or an OSObject *.
+  ArgEffects getOSOutParamsCreateRuleMap(const FunctionDecl *FD);
+
+  /// Create +0 arg effects to all OS object out parameters.
+  ArgEffects getOSOutParamsGetRuleMap(const FunctionDecl *FD);
+
   /// Create an OS object at +1.
   const RetainSummary *getOSSummaryCreateRule(const FunctionDecl *FD);
 
+  /// Create an OS object at +1 and create out-parameters at +1.
+  const RetainSummary *
+  getOSSummaryCreateRuleWithOutParams(const FunctionDecl *FD);
+
+  /// Create an OS object at +0 and create out-parameters at +0.
+  const RetainSummary *getOSSummaryGetRuleWithOutParams(const FunctionDecl *FD);
+
   /// Get an OS object at +0.
   const RetainSummary *getOSSummaryGetRule(const FunctionDecl *FD);
 
+  /// Create out-parameters at +1, don't care about the return value.
+  const RetainSummary *
+  getOSSummaryCreateRuleOutParamsOnly(const FunctionDecl *FD);
+
+  /// Create out-parameters at +0, don't care about the return value.
+  const RetainSummary *getOSSummaryGetRuleOutParamsOnly(const FunctionDecl *FD);
+
   /// Increment the reference count on OS object.
   const RetainSummary *getOSSummaryRetainRule(const FunctionDecl *FD);
 
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
@@ -860,6 +860,7 @@
              .Case("macos", "macOS")
              .Case("tvos", "tvOS")
              .Case("watchos", "watchOS")
+             .Case("driverkit", "DriverKit")
              .Case("ios_app_extension", "iOS (App Extension)")
              .Case("macos_app_extension", "macOS (App Extension)")
              .Case("tvos_app_extension", "tvOS (App Extension)")
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
@@ -1551,6 +1551,10 @@
 ``watchos``
   Apple's watchOS operating system. The minimum deployment target is specified by
   the ``-mwatchos-version-min=*version*`` command-line argument.
+  
+``driverkit``
+  Apple's DriverKit userspace kernel extensions. The minimum deployment target
+  is specified as part of the triple.
 
 A declaration can typically be used even when deploying back to a platform
 version prior to when the declaration was introduced. When this happens, the
diff --git a/clang/include/clang/Basic/Features.def b/clang/include/clang/Basic/Features.def
--- a/clang/include/clang/Basic/Features.def
+++ b/clang/include/clang/Basic/Features.def
@@ -58,6 +58,7 @@
 FEATURE(attribute_availability_with_version_underscores, true)
 FEATURE(attribute_availability_tvos, true)
 FEATURE(attribute_availability_watchos, true)
+FEATURE(attribute_availability_driverkit, true)
 FEATURE(attribute_availability_with_strict, true)
 FEATURE(attribute_availability_with_replacement, true)
 FEATURE(attribute_availability_in_templates, true)
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -3850,6 +3850,7 @@
   HelpText<"Do not link device library for CUDA/HIP device compilation">;
 def : Flag<["-"], "nocudalib">, Alias<nogpulib>;
 def nodefaultlibs : Flag<["-"], "nodefaultlibs">;
+def nodriverkitlib : Flag<["-"], "nodriverkitlib">;
 def nofixprebinding : Flag<["-"], "nofixprebinding">;
 def nolibc : Flag<["-"], "nolibc">;
 def nomultidefs : Flag<["-"], "nomultidefs">;
diff --git a/clang/lib/Analysis/RetainSummaryManager.cpp b/clang/lib/Analysis/RetainSummaryManager.cpp
--- a/clang/lib/Analysis/RetainSummaryManager.cpp
+++ b/clang/lib/Analysis/RetainSummaryManager.cpp
@@ -19,6 +19,7 @@
 #include "clang/AST/DeclObjC.h"
 #include "clang/AST/ParentMap.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/Basic/TargetInfo.h"
 
 using namespace clang;
 using namespace ento;
@@ -238,12 +239,25 @@
   return false;
 }
 
+static bool isDriverKitGetter(StringRef FName) {
+  llvm::Regex Re("(.*)Get([A-Z_]|$)(.*)");
+  return FName.startswith("get") || Re.match(FName);
+}
+
 const RetainSummary *
 RetainSummaryManager::getSummaryForOSObject(const FunctionDecl *FD,
                                             StringRef FName, QualType RetTy) {
   assert(TrackOSObjects &&
          "Requesting a summary for an OSObject but OSObjects are not tracked");
 
+  if (Ctx.getTargetInfo().getTriple().isDriverKit()) {
+    const FunctionType *FT = FD->getType()->getAs<FunctionType>();
+    if (FName == "OSObjectRetain")
+      return getUnarySummary(FT, IncRef);
+    if (FName == "OSObjectRelease")
+      return getUnarySummary(FT, DecRef);
+  }
+
   if (RetTy->isPointerType()) {
     const CXXRecordDecl *PD = RetTy->getPointeeType()->getAsCXXRecordDecl();
     if (PD && isOSObjectSubclass(PD)) {
@@ -258,15 +272,32 @@
         return getPersistentStopSummary();
       }
 
-      // All objects returned with functions *not* starting with 'get',
-      // or iterators, are returned at +1.
-      if ((!FName.startswith("get") && !FName.startswith("Get")) ||
-          isOSIteratorSubclass(PD)) {
-        return getOSSummaryCreateRule(FD);
+      if (Ctx.getTargetInfo().getTriple().isDriverKit()) {
+        if (isDriverKitGetter(FName) || isOSIteratorSubclass(PD))
+          return getOSSummaryGetRuleWithOutParams(FD);
+        else
+          return getOSSummaryCreateRuleWithOutParams(FD);
       } else {
-        return getOSSummaryGetRule(FD);
+        // All objects returned with functions *not* starting with 'get',
+        // or iterators, are returned at +1.
+        if ((!FName.startswith("get") && !FName.startswith("Get")) ||
+            isOSIteratorSubclass(PD)) {
+          return getOSSummaryCreateRule(FD);
+        } else {
+          return getOSSummaryGetRule(FD);
+        }
       }
     }
+  } else if (Ctx.getTargetInfo().getTriple().isDriverKit()) {
+    // Under DriverKit we assume the create rule (depending on return values)
+    // for out-parameters by default.
+    if (isDriverKitGetter(FName)) {
+      if (const RetainSummary *Summ = getOSSummaryGetRuleOutParamsOnly(FD))
+        return Summ;
+    } else {
+      if (const RetainSummary *Summ = getOSSummaryCreateRuleOutParamsOnly(FD))
+        return Summ;
+    }
   }
 
   if (const auto *MD = dyn_cast<CXXMethodDecl>(FD)) {
@@ -757,6 +788,9 @@
     // or that it returns zero (when the cast failed, or the input
     // was zero).
     if (TrackOSObjects) {
+      if (FName == "OSObjectRetain" || FName == "OSObjectRelease")
+        return BehaviorSummary::NoOp;
+
       if (isOSObjectDynamicCast(FName) && FD->param_size() >= 1) {
         return BehaviorSummary::IdentityOrZero;
       } else if (isOSObjectRequiredCast(FName) && FD->param_size() >= 1) {
@@ -805,6 +839,58 @@
                               ArgEffect(DoNothing), ArgEffect(DoNothing));
 }
 
+/// \return Whether the chain of typedefs starting from @c QT
+/// has a typedef with a given name @c Name.
+static bool hasTypedefNamed(QualType QT,
+                            StringRef Name) {
+  while (auto *T = dyn_cast<TypedefType>(QT)) {
+    const auto &Context = T->getDecl()->getASTContext();
+    if (T->getDecl()->getIdentifier() == &Context.Idents.get(Name))
+      return true;
+    QT = T->getDecl()->getUnderlyingType();
+  }
+  return false;
+}
+
+ArgEffects RetainSummaryManager::getOSOutParametersMap(const FunctionDecl *FD,
+                                                       ArgEffectKind AEK) {
+  ArgEffects AE = AF.getEmptyMap();
+  for (unsigned I = 0, E = FD->getNumParams(); I != E; ++I) {
+    QualType T = FD->parameters()[I]->getType();
+    if (!T->isPointerType())
+      continue;
+    
+    T = T->getPointeeType();
+    // If it's a const pointer, it's not an out-parameter,
+    // because you cannot write into a const pointer.
+    if (T.isConstQualified() || !isOSObjectPtr(T))
+      continue;
+
+    AE = AF.add(AE, I, ArgEffect(AEK, ObjKind::OS));
+  }
+  return AE;
+}
+
+ArgEffects
+RetainSummaryManager::getOSOutParamsCreateRuleMap(const FunctionDecl *FD) {
+  QualType RT = FD->getReturnType();
+  ArgEffectKind AEK = hasTypedefNamed(RT, "kern_return_t")
+                          ? RetainedOutParameterOnZero
+                          : (isOSObjectPtr(RT) || RT->isBooleanType())
+                                ? RetainedOutParameterOnNonZero
+                                : RetainedOutParameter;
+  return getOSOutParametersMap(FD, AEK);
+}
+
+ArgEffects
+RetainSummaryManager::getOSOutParamsGetRuleMap(const FunctionDecl *FD) {
+  // Here we assume that if the function follows the "Get" rule,
+  // the rule is also applied to out-parameters. It sounds intuitive
+  // and easy to remember that the same rules apply regardless of
+  // how is the value returned.
+  return getOSOutParametersMap(FD, UnretainedOutParameter);
+}
+
 const RetainSummary *
 RetainSummaryManager::getOSSummaryRetainRule(const FunctionDecl *FD) {
   return getPersistentSummary(RetEffect::MakeNoRet(),
@@ -838,12 +924,44 @@
                               AF.getEmptyMap());
 }
 
+const RetainSummary *RetainSummaryManager::getOSSummaryCreateRuleWithOutParams(
+    const FunctionDecl *FD) {
+  return getPersistentSummary(RetEffect::MakeOwned(ObjKind::OS),
+                              getOSOutParamsCreateRuleMap(FD));
+}
+
 const RetainSummary *
 RetainSummaryManager::getOSSummaryGetRule(const FunctionDecl *FD) {
   return getPersistentSummary(RetEffect::MakeNotOwned(ObjKind::OS),
                               AF.getEmptyMap());
 }
 
+const RetainSummary *
+RetainSummaryManager::getOSSummaryGetRuleWithOutParams(const FunctionDecl *FD) {
+  return getPersistentSummary(RetEffect::MakeNotOwned(ObjKind::OS),
+                              getOSOutParamsGetRuleMap(FD));
+}
+
+const RetainSummary *RetainSummaryManager::getOSSummaryCreateRuleOutParamsOnly(
+    const FunctionDecl *FD) {
+  ArgEffects AE = getOSOutParamsCreateRuleMap(FD);
+  // If this function has no OSObject out-parameters, we shouldn't model it,
+  // because there's nothing remaining to model.
+  if (AE.isEmpty())
+    return nullptr;
+  return getPersistentSummary(RetEffect::MakeNoRet(), AE);
+}
+
+const RetainSummary *RetainSummaryManager::getOSSummaryGetRuleOutParamsOnly(
+    const FunctionDecl *FD) {
+  ArgEffects AE = getOSOutParamsGetRuleMap(FD);
+  // If this function has no OSObject out-parameters, we shouldn't model it,
+  // because there's nothing remaining to model.
+  if (AE.isEmpty())
+    return nullptr;
+  return getPersistentSummary(RetEffect::MakeNoRet(), AE);
+}
+
 const RetainSummary *
 RetainSummaryManager::getCFSummaryCreateRule(const FunctionDecl *FD) {
   return getPersistentSummary(RetEffect::MakeOwned(ObjKind::CF),
@@ -888,19 +1006,6 @@
   return None;
 }
 
-/// \return Whether the chain of typedefs starting from @c QT
-/// has a typedef with a given name @c Name.
-static bool hasTypedefNamed(QualType QT,
-                            StringRef Name) {
-  while (auto *T = dyn_cast<TypedefType>(QT)) {
-    const auto &Context = T->getDecl()->getASTContext();
-    if (T->getDecl()->getIdentifier() == &Context.Idents.get(Name))
-      return true;
-    QT = T->getDecl()->getUnderlyingType();
-  }
-  return false;
-}
-
 static QualType getCallableReturnType(const NamedDecl *ND) {
   if (const auto *FD = dyn_cast<FunctionDecl>(ND)) {
     return FD->getReturnType();
diff --git a/clang/lib/Basic/Targets/OSTargets.h b/clang/lib/Basic/Targets/OSTargets.h
--- a/clang/lib/Basic/Targets/OSTargets.h
+++ b/clang/lib/Basic/Targets/OSTargets.h
@@ -108,6 +108,8 @@
         this->TLSSupported = !Triple.isOSVersionLT(2);
       else
         this->TLSSupported = !Triple.isOSVersionLT(3);
+    } else if (Triple.isDriverKit()) {
+      // No TLS on DriverKit.
     }
 
     this->MCountName = "\01mcount";
diff --git a/clang/lib/Basic/Targets/OSTargets.cpp b/clang/lib/Basic/Targets/OSTargets.cpp
--- a/clang/lib/Basic/Targets/OSTargets.cpp
+++ b/clang/lib/Basic/Targets/OSTargets.cpp
@@ -104,6 +104,19 @@
     Str[4] = '0' + (OsVersion.getSubminor().getValueOr(0) % 10);
     Str[5] = '\0';
     Builder.defineMacro("__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__", Str);
+  } else if (Triple.isDriverKit()) {
+    assert(OsVersion.getMajor() < 100 &&
+           OsVersion.getMinor().getValueOr(0) < 100 &&
+           OsVersion.getSubminor().getValueOr(0) < 100 && "Invalid version!");
+    char Str[7];
+    Str[0] = '0' + (OsVersion.getMajor() / 10);
+    Str[1] = '0' + (OsVersion.getMajor() % 10);
+    Str[2] = '0' + (OsVersion.getMinor().getValueOr(0) / 10);
+    Str[3] = '0' + (OsVersion.getMinor().getValueOr(0) % 10);
+    Str[4] = '0' + (OsVersion.getSubminor().getValueOr(0) / 10);
+    Str[5] = '0' + (OsVersion.getSubminor().getValueOr(0) % 10);
+    Str[6] = '\0';
+    Builder.defineMacro("__ENVIRONMENT_DRIVERKIT_VERSION_MIN_REQUIRED__", Str);
   } else if (Triple.isMacOSX()) {
     // Note that the Driver allows versions which aren't representable in the
     // define (because we only get a single digit for the minor and micro
diff --git a/clang/lib/CodeGen/CGObjC.cpp b/clang/lib/CodeGen/CGObjC.cpp
--- a/clang/lib/CodeGen/CGObjC.cpp
+++ b/clang/lib/CodeGen/CGObjC.cpp
@@ -3896,6 +3896,8 @@
     return llvm::MachO::PLATFORM_TVOS;
   case llvm::Triple::WatchOS:
     return llvm::MachO::PLATFORM_WATCHOS;
+  case llvm::Triple::DriverKit:
+    return llvm::MachO::PLATFORM_DRIVERKIT;
   default:
     return /*Unknown platform*/ 0;
   }
@@ -3976,6 +3978,9 @@
   case llvm::Triple::MacOSX:
     FoundationDroppedInVersion = VersionTuple(/*Major=*/10, /*Minor=*/15);
     break;
+  case llvm::Triple::DriverKit:
+    // DriverKit doesn't need Foundation.
+    return false;
   default:
     llvm_unreachable("Unexpected OS");
   }
diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -5564,6 +5564,7 @@
     case llvm::Triple::IOS:
     case llvm::Triple::TvOS:
     case llvm::Triple::WatchOS:
+    case llvm::Triple::DriverKit:
       TC = std::make_unique<toolchains::DarwinClang>(*this, Target, Args);
       break;
     case llvm::Triple::DragonFly:
diff --git a/clang/lib/Driver/ToolChain.cpp b/clang/lib/Driver/ToolChain.cpp
--- a/clang/lib/Driver/ToolChain.cpp
+++ b/clang/lib/Driver/ToolChain.cpp
@@ -67,8 +67,9 @@
       return ToolChain::RM_Disabled;
   }
 
-  // -frtti is default, except for the PS4.
-  return (Triple.isPS4()) ? ToolChain::RM_Disabled : ToolChain::RM_Enabled;
+  // -frtti is default, except for the PS4 and DriverKit.
+  bool NoRTTI = Triple.isPS4() || Triple.isDriverKit();
+  return NoRTTI ? ToolChain::RM_Disabled : ToolChain::RM_Enabled;
 }
 
 ToolChain::ToolChain(const Driver &D, const llvm::Triple &T,
diff --git a/clang/lib/Driver/ToolChains/Arch/ARM.cpp b/clang/lib/Driver/ToolChains/Arch/ARM.cpp
--- a/clang/lib/Driver/ToolChains/Arch/ARM.cpp
+++ b/clang/lib/Driver/ToolChains/Arch/ARM.cpp
@@ -320,6 +320,7 @@
   case llvm::Triple::MacOSX:
   case llvm::Triple::IOS:
   case llvm::Triple::TvOS:
+  case llvm::Triple::DriverKit:
     // Darwin defaults to "softfp" for v6 and v7.
     if (Triple.isWatchABI())
       return FloatABI::Hard;
diff --git a/clang/lib/Driver/ToolChains/Arch/X86.cpp b/clang/lib/Driver/ToolChains/Arch/X86.cpp
--- a/clang/lib/Driver/ToolChains/Arch/X86.cpp
+++ b/clang/lib/Driver/ToolChains/Arch/X86.cpp
@@ -84,6 +84,10 @@
     // Simulators can still run on 10.11 though, like Xcode.
     if (Triple.isMacOSX() && !Triple.isOSVersionLT(10, 12))
       return "penryn";
+
+    if (Triple.isDriverKit())
+      return "nehalem";
+
     // The oldest x86_64 Macs have core2/Merom; the oldest x86 Macs have Yonah.
     return Is64Bit ? "core2" : "yonah";
   }
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -451,7 +451,7 @@
   if (types::isCXX(InputType)) {
     // Disable C++ EH by default on XCore and PS4.
     bool CXXExceptionsEnabled =
-        Triple.getArch() != llvm::Triple::xcore && !Triple.isPS4();
+        Triple.getArch() != llvm::Triple::xcore && !Triple.isPS4() && !Triple.isDriverKit();
     Arg *ExceptionArg = Args.getLastArg(
         options::OPT_fcxx_exceptions, options::OPT_fno_cxx_exceptions,
         options::OPT_fexceptions, options::OPT_fno_exceptions);
diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp b/clang/lib/Driver/ToolChains/CommonArgs.cpp
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -1249,7 +1249,7 @@
   // generation, independent of the argument order.
   if (KernelOrKext &&
       ((!EffectiveTriple.isiOS() || EffectiveTriple.isOSVersionLT(6)) &&
-       !EffectiveTriple.isWatchOS()))
+       !EffectiveTriple.isWatchOS() && !EffectiveTriple.isDriverKit()))
     PIC = PIE = false;
 
   if (Arg *A = Args.getLastArg(options::OPT_mdynamic_no_pic)) {
diff --git a/clang/lib/Driver/ToolChains/Darwin.h b/clang/lib/Driver/ToolChains/Darwin.h
--- a/clang/lib/Driver/ToolChains/Darwin.h
+++ b/clang/lib/Driver/ToolChains/Darwin.h
@@ -299,7 +299,8 @@
     IPhoneOS,
     TvOS,
     WatchOS,
-    LastDarwinPlatform = WatchOS
+    DriverKit,
+    LastDarwinPlatform = DriverKit
   };
   enum DarwinEnvironmentKind {
     NativeEnvironment,
@@ -349,7 +350,7 @@
 
   bool isKernelStatic() const override {
     return (!(isTargetIPhoneOS() && !isIPhoneOSVersionLT(6, 0)) &&
-            !isTargetWatchOS());
+            !isTargetWatchOS() && !isTargetDriverKit());
   }
 
   void addProfileRTLibs(const llvm::opt::ArgList &Args,
@@ -435,6 +436,11 @@
     return TargetPlatform == WatchOS;
   }
 
+  bool isTargetDriverKit() const {
+    assert(TargetInitialized && "Target not initialized!");
+    return TargetPlatform == DriverKit;
+  }
+
   bool isTargetMacCatalyst() const {
     return TargetPlatform == IPhoneOS && TargetEnvironment == MacCatalyst;
   }
@@ -538,7 +544,7 @@
   GetDefaultStackProtectorLevel(bool KernelOrKext) const override {
     // Stack protectors default to on for user code on 10.5,
     // and for everything in 10.6 and beyond
-    if (isTargetIOSBased() || isTargetWatchOSBased())
+    if (isTargetIOSBased() || isTargetWatchOSBased() || isTargetDriverKit())
       return LangOptions::SSPOn;
     else if (isTargetMacOSBased() && !isMacosxVersionLT(10, 6))
       return LangOptions::SSPOn;
diff --git a/clang/lib/Driver/ToolChains/Darwin.cpp b/clang/lib/Driver/ToolChains/Darwin.cpp
--- a/clang/lib/Driver/ToolChains/Darwin.cpp
+++ b/clang/lib/Driver/ToolChains/Darwin.cpp
@@ -712,6 +712,26 @@
     }
   }
 
+  // DriverKit's framework doesn't have the same layout as other frameworks.
+  // Add missing search paths if necessary.
+  if (getToolChain().getTriple().getOS() == llvm::Triple::DriverKit) {
+    if (const Arg *Root = Args.getLastArg(options::OPT_isysroot)) {
+      // ld64 fixed the implicit -F and -L paths in ld64-605.1+.
+      if (Version.getMajor() < 605 ||
+          (Version.getMajor() == 605 && Version.getMinor().getValueOr(0) < 1)) {
+
+        SmallString<128> L(Root->getValue());
+        llvm::sys::path::append(L, "System", "DriverKit", "usr", "lib");
+        CmdArgs.push_back(Args.MakeArgString(std::string("-L") + L));
+
+        SmallString<128> F(Root->getValue());
+        llvm::sys::path::append(F, "System", "DriverKit");
+        llvm::sys::path::append(F, "System", "Library", "Frameworks");
+        CmdArgs.push_back(Args.MakeArgString(std::string("-F") + F));
+      }
+    }
+  }
+
   ResponseFileSupport ResponseSupport;
   if (Version >= VersionTuple(705) || LinkerIsLLD) {
     ResponseSupport = ResponseFileSupport::AtFileUTF8();
@@ -872,7 +892,7 @@
   // Default to use libc++ on OS X 10.9+ and iOS 7+.
   if ((isTargetMacOSBased() && !isMacosxVersionLT(10, 9)) ||
       (isTargetIOSBased() && !isIPhoneOSVersionLT(7, 0)) ||
-      isTargetWatchOSBased())
+      isTargetWatchOSBased() || isTargetDriverKit())
     return ToolChain::CST_Libcxx;
 
   return ToolChain::CST_Libstdcxx;
@@ -891,7 +911,7 @@
 
 /// Darwin provides a blocks runtime starting in MacOS X 10.6 and iOS 3.2.
 bool Darwin::hasBlocksRuntime() const {
-  if (isTargetWatchOSBased())
+  if (isTargetWatchOSBased() || isTargetDriverKit())
     return true;
   else if (isTargetIOSBased())
     return !isIPhoneOSVersionLT(3, 2);
@@ -1018,6 +1038,8 @@
     Str += "watchos";
   else if (isTargetTvOSBased())
     Str += "tvos";
+  else if (isTargetDriverKit())
+    Str += "driverkit";
   else if (isTargetIOSBased() || isTargetMacCatalyst())
     Str += "ios";
   else
@@ -1219,6 +1241,8 @@
       return "AppleTV";
     case DarwinPlatformKind::WatchOS:
       return "Watch";
+    case DarwinPlatformKind::DriverKit:
+      return "DriverKit";
   }
   llvm_unreachable("Unsupported platform");
 }
@@ -1250,6 +1274,8 @@
   case DarwinPlatformKind::WatchOS:
     return TargetEnvironment == NativeEnvironment || IgnoreSim ? "watchos"
                                                                : "watchossim";
+  case DarwinPlatformKind::DriverKit:
+    return "driverkit";
   }
   llvm_unreachable("Unsupported platform");
 }
@@ -1407,9 +1433,15 @@
     AddLinkRuntimeLib(Args, CmdArgs, "xray-fdr");
   }
 
+  if (isTargetDriverKit() && !Args.hasArg(options::OPT_nodriverkitlib)) {
+    CmdArgs.push_back("-framework");
+    CmdArgs.push_back("DriverKit");
+  }
+
   // Otherwise link libSystem, then the dynamic runtime library, and finally any
   // target specific static runtime library.
-  CmdArgs.push_back("-lSystem");
+  if (!isTargetDriverKit())
+    CmdArgs.push_back("-lSystem");
 
   // Select the dynamic runtime library and the target specific static library.
   if (isTargetIOSBased()) {
@@ -1524,6 +1556,9 @@
     case DarwinPlatformKind::WatchOS:
       Opt = options::OPT_mwatchos_version_min_EQ;
       break;
+    case DarwinPlatformKind::DriverKit:
+      // DriverKit always explicitly provides a version in the triple.
+      return;
     }
     Argument = Args.MakeJoinedArg(nullptr, Opts.getOption(Opt), OSVersion);
     Args.append(Argument);
@@ -1663,6 +1698,8 @@
       return DarwinPlatformKind::TvOS;
     case llvm::Triple::WatchOS:
       return DarwinPlatformKind::WatchOS;
+    case llvm::Triple::DriverKit:
+      return DarwinPlatformKind::DriverKit;
     default:
       llvm_unreachable("Unable to infer Darwin variant");
     }
@@ -1732,6 +1769,7 @@
       "IPHONEOS_DEPLOYMENT_TARGET",
       "TVOS_DEPLOYMENT_TARGET",
       "WATCHOS_DEPLOYMENT_TARGET",
+      "DRIVERKIT_DEPLOYMENT_TARGET",
   };
   static_assert(llvm::array_lengthof(EnvVars) == Darwin::LastDarwinPlatform + 1,
                 "Missing platform");
@@ -1830,6 +1868,8 @@
       return DarwinPlatform::createFromSDK(
           Darwin::TvOS, Version,
           /*IsSimulator=*/SDK.startswith("AppleTVSimulator"));
+    else if (SDK.startswith("DriverKit"))
+      return DarwinPlatform::createFromSDK(Darwin::DriverKit, Version);
     return None;
   };
   if (auto Result = CreatePlatformFromSDKName(SDK))
@@ -1866,6 +1906,9 @@
   case llvm::Triple::WatchOS:
     OsVersion = Triple.getWatchOSVersion();
     break;
+  case llvm::Triple::DriverKit:
+    OsVersion = Triple.getDriverKitVersion();
+    break;
   default:
     llvm_unreachable("Unexpected OS type");
     break;
@@ -2167,12 +2210,19 @@
         HadExtra || Major >= 10 || Minor >= 100 || Micro >= 100)
       getDriver().Diag(diag::err_drv_invalid_version_number)
           << OSTarget->getAsString(Args, Opts);
+  } else if (Platform == DriverKit) {
+    if (!Driver::GetReleaseVersion(OSTarget->getOSVersion(), Major, Minor,
+                                   Micro, HadExtra) ||
+        HadExtra || Major < 19 || Major >= 100 || Minor >= 100 || Micro >= 100)
+      getDriver().Diag(diag::err_drv_invalid_version_number)
+          << OSTarget->getAsString(Args, Opts);
   } else
     llvm_unreachable("unknown kind of Darwin platform");
 
   DarwinEnvironmentKind Environment = OSTarget->getEnvironment();
   // Recognize iOS targets with an x86 architecture as the iOS simulator.
   if (Environment == NativeEnvironment && Platform != MacOS &&
+      Platform != DriverKit &&
       OSTarget->canInferSimulatorFromArch() && getTriple().isX86())
     Environment = Simulator;
 
@@ -2460,6 +2510,8 @@
     llvm::sys::path::append(P, "libclang_rt.cc_kext_tvos.a");
   } else if (isTargetIPhoneOS()) {
     llvm::sys::path::append(P, "libclang_rt.cc_kext_ios.a");
+  } else if (isTargetDriverKit()) {
+    // DriverKit doesn't want extra runtime support.
   } else {
     llvm::sys::path::append(P, "libclang_rt.cc_kext.a");
   }
@@ -2682,6 +2734,8 @@
   case WatchOS: // Earlier than 4.0.
     OS = llvm::Triple::WatchOS;
     break;
+  case DriverKit: // Always available.
+    return false;
   }
 
   return TargetVersion < alignedAllocMinVersion(OS);
@@ -2781,7 +2835,7 @@
   // FIXME: It would be far better to avoid inserting those -static arguments,
   // but we can't check the deployment target in the translation code until
   // it is set here.
-  if (isTargetWatchOSBased() ||
+  if (isTargetWatchOSBased() || isTargetDriverKit() ||
       (isTargetIOSBased() && !isIPhoneOSVersionLT(6, 0))) {
     for (ArgList::iterator it = DAL->begin(), ie = DAL->end(); it != ie; ) {
       Arg *A = *it;
@@ -2897,6 +2951,8 @@
     CmdArgs.push_back("-tvos_version_min");
   else if (isTargetTvOSSimulator())
     CmdArgs.push_back("-tvos_simulator_version_min");
+  else if (isTargetDriverKit())
+    CmdArgs.push_back("-driverkit_version_min");
   else if (isTargetIOSSimulator())
     CmdArgs.push_back("-ios_simulator_version_min");
   else if (isTargetIOSBased())
@@ -2946,6 +3002,8 @@
     return "tvos";
   case Darwin::WatchOS:
     return "watchos";
+  case Darwin::DriverKit:
+    return "driverkit";
   }
   llvm_unreachable("invalid platform");
 }
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
@@ -3163,7 +3163,10 @@
 #if defined(CLANG_DEFAULT_STD_CXX)
       LangStd = CLANG_DEFAULT_STD_CXX;
 #else
-      LangStd = LangStandard::lang_gnucxx14;
+      if (T.isDriverKit())
+        LangStd = LangStandard::lang_gnucxx17;
+      else
+        LangStd = LangStandard::lang_gnucxx14;
 #endif
       break;
     case Language::RenderScript:
diff --git a/clang/test/Analysis/driverkit_base.h b/clang/test/Analysis/driverkit_base.h
new file mode 100644
--- /dev/null
+++ b/clang/test/Analysis/driverkit_base.h
@@ -0,0 +1,22 @@
+#ifndef _DRIVERKIT_BASE
+#define _DRIVERKIT_BASE
+
+using OSObjectPtr = OSObject *;
+
+void OSObjectRetain(OSObjectPtr container);
+void OSObjectRelease(OSObjectPtr container);
+
+#define OSObjectSafeReleaseNULL(ptr) \
+  do {                               \
+    if ((ptr)) {                     \
+      OSObjectRelease(ptr);          \
+      (ptr) = NULL;                  \
+    }                                \
+  } while (0)
+
+class OSDictionary : public OSObject {};
+using OSDictionaryPtr = OSDictionary *;
+OSDictionaryPtr OSDictionaryCreate();
+OSObjectPtr OSDictionaryGetValue(OSDictionaryPtr obj, const char *key);
+
+#endif // _DRIVERKIT_BASE
diff --git a/clang/test/Analysis/retain-release-driverkit.cpp b/clang/test/Analysis/retain-release-driverkit.cpp
new file mode 100644
--- /dev/null
+++ b/clang/test/Analysis/retain-release-driverkit.cpp
@@ -0,0 +1,76 @@
+// RUN: %clang_analyze_cc1 -w -triple x86_64-apple-driverkit19.0 \
+// RUN:   -analyzer-checker=core,osx -verify %s
+
+#include "os_object_base.h"
+#include "driverkit_base.h"
+
+typedef kern_return_t IOReturn;
+#define kIOReturnSuccess 0
+
+void test_driverkit_naming_conventions(OSDictionary *Dict) {
+  OSDictionaryGetValue(Dict, "key"); // no-warning
+  OSDictionaryPtr Dict2 = OSDictionaryCreate(); // expected-warning{{Potential leak of an object stored into 'Dict2'}}
+}
+
+void test_driverkit_retain_release() {
+  OSDictionaryPtr Dict = OSDictionaryCreate();
+  OSObjectRetain(Dict);
+  OSObjectRelease(Dict);
+  OSObjectRelease(Dict);
+}
+
+IOReturn make_out_param_and_ioreturn(OSObject **obj);
+OSObject *make_out_param_and_osobject(OSObject **obj);
+bool make_out_param_and_bool(OSObject **obj);
+void just_make_out_param(OSObject **obj);
+void get_out_param(OSObject **obj);
+void get_out_param_annotated(__attribute__((os_returns_retained)) OSObject **obj);
+IOReturn get_out_param_and_ioreturn(OSObject **obj);
+
+void test_out_param_conventions() {
+  OSObject *Obj = nullptr;
+  // Don't warn when the function returned a failure.
+  IOReturn ret = make_out_param_and_ioreturn(&Obj); // no-warning
+  if (ret == kIOReturnSuccess)
+    OSObjectRelease(Obj);
+
+  // Warn if the return value is unchecked.
+  make_out_param_and_ioreturn(&Obj); // expected-warning{{Potential leak of an object stored into 'Obj'}}
+
+  // If it looks like a getter, treat it as +0.
+  OSObject *Obj2;
+  ret = get_out_param_and_ioreturn(&Obj2);
+  if (ret == kIOReturnSuccess)
+    OSObjectRelease(Obj2); // expected-warning{{Incorrect decrement of the reference count of an object that is not owned at this point by the caller}}
+
+  // Treat "true" as success, "false" as failure by default.
+  bool b = make_out_param_and_bool(&Obj2); // no-warning
+  if (b)
+    OSObjectRelease(Obj2);
+
+  // Warn only when the object that was returned directly
+  // has turned out to be valid (or nobody cared).
+  OSObject *Obj3; // Let's also see what happens if it's uninitialized.
+  OSObject *Obj4 = make_out_param_and_osobject(&Obj3); // no-warning
+  if (Obj4) {
+    OSObjectRelease(Obj3); // no-warning
+    OSObjectRelease(Obj4); // no-warning
+  }
+
+  make_out_param_and_osobject(&Obj3); // expected-warning{{Potential leak of an object of type 'OSObject'}}
+                                      // expected-warning@-1{{Potential leak of an object stored into 'Obj3'}}
+
+  // When there's no return value, always treat it as +1...
+  OSObject *Obj5 = nullptr;
+  just_make_out_param(&Obj5); // expected-warning{{Potential leak of an object stored into 'Obj5'}}
+
+  // ...unless it looks like a getter, in this case treat it as +0.
+  OSObject *Obj6 = nullptr;
+  get_out_param(&Obj6); // no-warning
+  if (Obj6)
+    OSObjectRelease(Obj6); // expected-warning{{Incorrect decrement of the reference count of an object that is not owned at this point by the caller}}
+
+  OSObject *Obj7 = nullptr;
+  get_out_param_annotated(&Obj7);
+  OSObjectRelease(Obj7); // no-warning
+}
diff --git a/clang/test/CodeGen/availability-check-driverkit.c b/clang/test/CodeGen/availability-check-driverkit.c
new file mode 100644
--- /dev/null
+++ b/clang/test/CodeGen/availability-check-driverkit.c
@@ -0,0 +1,10 @@
+// RUN: %clang_cc1 -triple x86_64-apple-driverkit19.0 -emit-llvm -o - %s | FileCheck %s
+
+void use_at_available() {
+  // CHECK: call i32 @__isPlatformVersionAtLeast(i32 10, i32 19, i32 1, i32 0)
+  // CHECK-NEXT: icmp ne
+  if (__builtin_available(driverkit 19.1, *))
+    ;
+}
+
+// CHECK: declare i32 @__isPlatformVersionAtLeast(i32, i32, i32, i32)
diff --git a/clang/test/Driver/Inputs/DriverKit19.0.sdk/SDKSettings.plist b/clang/test/Driver/Inputs/DriverKit19.0.sdk/SDKSettings.plist
new file mode 100644
diff --git a/clang/test/Driver/Inputs/DriverKit19.0.sdk/System/DriverKit/usr/include/.keep b/clang/test/Driver/Inputs/DriverKit19.0.sdk/System/DriverKit/usr/include/.keep
new file mode 100644
diff --git a/clang/test/Driver/Inputs/basic_darwin_driverkit_sdk_usr_cxx_v1/System/DriverKit/usr/include/c++/v1/.keep b/clang/test/Driver/Inputs/basic_darwin_driverkit_sdk_usr_cxx_v1/System/DriverKit/usr/include/c++/v1/.keep
new file mode 100644
diff --git a/clang/test/Driver/Inputs/basic_darwin_driverkit_sdk_usr_cxx_v1/System/DriverKit/usr/lib/.keep b/clang/test/Driver/Inputs/basic_darwin_driverkit_sdk_usr_cxx_v1/System/DriverKit/usr/lib/.keep
new file mode 100644
diff --git a/clang/test/Driver/Inputs/resource_dir/lib/darwin/libclang_rt.driverkit.a b/clang/test/Driver/Inputs/resource_dir/lib/darwin/libclang_rt.driverkit.a
new file mode 100644
diff --git a/clang/test/Driver/darwin-ld-platform-version-driverkit.c b/clang/test/Driver/darwin-ld-platform-version-driverkit.c
new file mode 100644
--- /dev/null
+++ b/clang/test/Driver/darwin-ld-platform-version-driverkit.c
@@ -0,0 +1,20 @@
+// RUN: touch %t.o
+
+// RUN: %clang -target x86_64-apple-driverkit10.15 -isysroot %S/Inputs/MacOSX10.14.sdk -mlinker-version=520 -### %t.o 2>&1 \
+// RUN:   | FileCheck %s
+// RUN: mkdir -p %t.sdk
+// RUN: %clang -target x86_64-apple-driverkit19 -isysroot %t.sdk -mlinker-version=520 -### %t.o 2>&1 \
+// RUN:   | FileCheck --check-prefix=MISSING-SDK-JSON-WORKAROUND %s
+
+// RUN: %clang -target arm64-apple-driverkit19 -isysroot %S/Inputs/MacOSX10.14.sdk -mlinker-version=520 -### %t.o 2>&1 \
+// RUN:   | FileCheck --check-prefix=ARM64_NEW %s
+// RUN: %clang -target arm64-apple-driverkit19 -isysroot %S/Inputs/MacOSX10.14.sdk -mlinker-version=400 -### %t.o 2>&1 \
+// RUN:   | FileCheck --check-prefix=ARM64_OLD %s
+// RUN: %clang -target arm64e-apple-driverkit19 -isysroot %S/Inputs/MacOSX10.14.sdk -mlinker-version=520 -### %t.o 2>&1 \
+// RUN:   | FileCheck --check-prefix=ARM64_NEW %s
+
+// CHECK: "-platform_version" "driverkit" "10.15.0" "10.14"
+// MISSING-SDK-JSON-WORKAROUND: "-platform_version" "driverkit" "19.0.0" "19.0.0"
+
+// ARM64_NEW: "-platform_version" "driverkit" "20.0.0" "10.14"
+// ARM64_OLD: "-driverkit_version_min" "20.0.0"
diff --git a/clang/test/Driver/darwin-ld.c b/clang/test/Driver/darwin-ld.c
--- a/clang/test/Driver/darwin-ld.c
+++ b/clang/test/Driver/darwin-ld.c
@@ -185,6 +185,15 @@
 // LINK_TVOS_KEXT: libclang_rt.cc_kext_tvos.a
 // LINK_TVOS_KEXT: libclang_rt.tvos.a
 
+// RUN: %clang -target x86-64-apple-driverkit19.0 -mlinker-version=400 -resource-dir=%S/Inputs/resource_dir -### %t.o 2> %t.log
+// RUN: FileCheck -check-prefix=LINK_DRIVERKIT %s < %t.log
+// LINK_DRIVERKIT: {{ld(.exe)?"}}
+// LINK_DRIVERKIT: -driverkit_version_min
+// LINK_DRIVERKIT-NOT: crt
+// LINK_DRIVERKIT-NOT: lgcc_s.1
+// LINK_DRIVERKIT-NOT: lSystem
+// LINK_DRIVERKIT: libclang_rt.driverkit.a
+
 // RUN: %clang -target armv7k-apple-watchos2.0 -fuse-ld= -mlinker-version=400 -mwatchos-version-min=2.0 -resource-dir=%S/Inputs/resource_dir -### %t.o 2> %t.log
 // RUN: FileCheck -check-prefix=LINK_WATCHOS_ARM %s < %t.log
 // LINK_WATCHOS_ARM: {{ld(.exe)?"}}
diff --git a/clang/test/Driver/darwin-version.c b/clang/test/Driver/darwin-version.c
--- a/clang/test/Driver/darwin-version.c
+++ b/clang/test/Driver/darwin-version.c
@@ -98,6 +98,10 @@
 // RUN:   FileCheck --check-prefix=CHECK-VERSION-WATCHSIM20 %s
 // CHECK-VERSION-WATCHSIM20: "i386-apple-watchos2.0.0-simulator"
 
+// RUN: %clang -target x86_64-apple-driverkit19.0 -c %s -### 2>&1 | \
+// RUN:   FileCheck --check-prefix=CHECK-VERSION-DRIVERKIT190 %s
+// CHECK-VERSION-DRIVERKIT190: "x86_64-apple-driverkit19.0.0"
+
 // Check environment variable gets interpreted correctly
 // RUN: env MACOSX_DEPLOYMENT_TARGET=10.5 IPHONEOS_DEPLOYMENT_TARGET=2.0 \
 // RUN:   %clang -target i686-apple-darwin9 -c %s -### 2>&1 | \
@@ -145,6 +149,15 @@
 // RUN: FileCheck --check-prefix=CHECK-VERSION-WATCHOS-TARGET %s
 // CHECK-VERSION-WATCHOS-TARGET: "x86_64-apple-watchos4.0.0-simulator"
 
+// RUN: env DRIVERKIT_DEPLOYMENT_TARGET=19.0 \
+// RUN:   %clang -target x86_64-apple-darwin -c %s -### 2>&1 | \
+// RUN:   FileCheck --check-prefix=CHECK-VERSION-DRIVERKIT %s
+// CHECK-VERSION-DRIVERKIT: "x86_64-apple-driverkit19.0.0"
+//
+// Make sure stdlib is not mistaken
+// RUN: env DRIVERKIT_DEPLOYMENT_TARGET=2.0 \
+// RUN:   %clang -target arm64-apple-darwin -c -x c++ %s -stdlib=libc++ -### 2>&1
+
 // RUN: env MACOSX_DEPLOYMENT_TARGET=1000.1000 \
 // RUN:   %clang -target x86_64-apple-darwin -c %s -### 2>&1 | \
 // RUN:   FileCheck --check-prefix=CHECK-VERSION-INVALID-ENV %s
diff --git a/clang/test/Driver/debug-options.c b/clang/test/Driver/debug-options.c
--- a/clang/test/Driver/debug-options.c
+++ b/clang/test/Driver/debug-options.c
@@ -66,6 +66,9 @@
 // RUN: %clang -### -c -g %s -target arm64-apple-tvos9.0 2>&1 \
 // RUN:             | FileCheck -check-prefix=G_STANDALONE \
 // RUN:                         -check-prefix=G_DWARF4 %s
+// RUN: %clang -### -c -g %s -target x86_64-apple-driverkit19.0 2>&1 \
+// RUN:             | FileCheck -check-prefix=G_STANDALONE \
+// RUN:                         -check-prefix=G_DWARF4 %s
 // RUN: %clang -### -c -fsave-optimization-record %s \
 // RUN:        -target x86_64-apple-darwin 2>&1 \
 // RUN:             | FileCheck -check-prefix=GLTO_ONLY %s
diff --git a/clang/test/Driver/driverkit-arm64.c b/clang/test/Driver/driverkit-arm64.c
new file mode 100644
--- /dev/null
+++ b/clang/test/Driver/driverkit-arm64.c
@@ -0,0 +1,4 @@
+// REQUIRES: aarch64-registered-target
+// RUN: %clang %s -target arm64-apple-driverkit -### 2>&1 | FileCheck %s
+
+// CHECK: "-target-cpu" "apple-a7"
diff --git a/clang/test/Driver/driverkit-arm64e.c b/clang/test/Driver/driverkit-arm64e.c
new file mode 100644
--- /dev/null
+++ b/clang/test/Driver/driverkit-arm64e.c
@@ -0,0 +1,4 @@
+// REQUIRES: aarch64-registered-target
+// RUN: %clang %s -target arm64e-apple-driverkit -### 2>&1 | FileCheck %s
+
+// CHECK: "-target-cpu" "apple-a12"
diff --git a/clang/test/Driver/driverkit-armv7k.s b/clang/test/Driver/driverkit-armv7k.s
new file mode 100644
--- /dev/null
+++ b/clang/test/Driver/driverkit-armv7k.s
@@ -0,0 +1,5 @@
+// RUN: %clang -c -x assembler-with-cpp -target armv7k-apple-driverkit21.0 -### %s 2>&1 | FileCheck %s
+// CHECK: -cc1as
+// CHECK-SAME: "-target-cpu" "cortex-a7"
+.foo:
+vfms.f64 d1, d0, d3
\ No newline at end of file
diff --git a/clang/test/Driver/driverkit-cplusplus.cpp b/clang/test/Driver/driverkit-cplusplus.cpp
new file mode 100644
--- /dev/null
+++ b/clang/test/Driver/driverkit-cplusplus.cpp
@@ -0,0 +1,8 @@
+// REQUIRES: x86-registered-target
+// RUN: %clang %s -target x86_64-apple-driverkit19.0 -fsyntax-only
+
+#if __cplusplus != 201703L
+#error DriverKit should be on C++17.
+#endif
+
+int main() { return 0; }
diff --git a/clang/test/Driver/driverkit-exceptions.cpp b/clang/test/Driver/driverkit-exceptions.cpp
new file mode 100644
--- /dev/null
+++ b/clang/test/Driver/driverkit-exceptions.cpp
@@ -0,0 +1,9 @@
+// REQUIRES: x86-registered-target
+// RUN: %clang %s -target x86_64-apple-driverkit19.0 -### 2>&1 | FileCheck %s -check-prefix=DEFAULT
+// RUN: %clang %s -target x86_64-apple-driverkit19.0 -fexceptions -### 2>&1 | FileCheck %s -check-prefix=USERPROVIDED
+
+int main() { return 0; }
+// DEFAULT-NOT: "-fcxx-exceptions"
+// DEFAULT-NOT: "-fexceptions"
+// USERPROVIDED: "-fcxx-exceptions"
+// USERPROVIDED: "-fexceptions"
diff --git a/clang/test/Driver/driverkit-framework.c b/clang/test/Driver/driverkit-framework.c
new file mode 100644
--- /dev/null
+++ b/clang/test/Driver/driverkit-framework.c
@@ -0,0 +1,13 @@
+// RUN: %clang %s -target x86_64-apple-driverkit19.0 \
+// RUN:   -isysroot %S/Inputs/DriverKit19.0.sdk -### 2>&1 \
+// RUN: | FileCheck %s -check-prefix=CHECK-DEFAULT
+
+// RUN: %clang %s -target x86_64-apple-driverkit19.0 -nodriverkitlib \
+// RUN:   -isysroot %S/Inputs/DriverKit19.0.sdk -### 2>&1 \
+// RUN: | FileCheck %s -check-prefix=CHECK-NO-DRIVERKIT
+
+int main() { return 0; }
+
+// CHECK-DEFAULT: "-framework" "DriverKit"
+
+// CHECK-NO-DRIVERKIT-NOT: "-framework" "DriverKit"
diff --git a/clang/test/Driver/driverkit-rtti.cpp b/clang/test/Driver/driverkit-rtti.cpp
new file mode 100644
--- /dev/null
+++ b/clang/test/Driver/driverkit-rtti.cpp
@@ -0,0 +1,5 @@
+// REQUIRES: x86-registered-target
+// RUN: %clang %s -target x86_64-apple-driverkit19.0 -### 2>&1 | FileCheck %s
+
+int main() { return 0; }
+// CHECK: "-fno-rtti"
diff --git a/clang/test/Driver/driverkit-target-cpu.c b/clang/test/Driver/driverkit-target-cpu.c
new file mode 100644
--- /dev/null
+++ b/clang/test/Driver/driverkit-target-cpu.c
@@ -0,0 +1,5 @@
+// REQUIRES: x86-registered-target
+// RUN: %clang %s -target x86_64-apple-driverkit19.0 -### 2>&1 | FileCheck %s
+
+int main() { return 0; }
+// CHECK: "-target-cpu" "nehalem"
diff --git a/clang/test/Driver/driverkit-version-min.c b/clang/test/Driver/driverkit-version-min.c
new file mode 100644
--- /dev/null
+++ b/clang/test/Driver/driverkit-version-min.c
@@ -0,0 +1,5 @@
+// REQUIRES: x86-registered-target
+// RUN: %clang -target x86_64-apple-driverkit19.0 -S -o - %s | FileCheck %s
+
+int main() { return 0; }
+// CHECK: .build_version driverkit, 19, 0
diff --git a/clang/test/Driver/incompatible_sysroot.c b/clang/test/Driver/incompatible_sysroot.c
--- a/clang/test/Driver/incompatible_sysroot.c
+++ b/clang/test/Driver/incompatible_sysroot.c
@@ -4,6 +4,8 @@
 // RUN: %clang -target x86_64-apple-darwin -Wincompatible-sysroot -isysroot SDKs/MacOSX10.9.sdk -mios-version-min=9.0 -S -o - %s 2>&1 | FileCheck -check-prefix CHECK-OSX-IOS %s
 // RUN: %clang -target arm64-apple-darwin -Wincompatible-sysroot -isysroot SDKs/iPhoneOS9.2.sdk -mwatchos-version-min=2.0 -S -o - %s 2>&1 | FileCheck -check-prefix CHECK-IOS-WATCHOS %s
 // RUN: %clang -target arm64-apple-darwin -Wincompatible-sysroot -isysroot SDKs/iPhoneOS9.2.sdk -mtvos-version-min=9.0 -S -o - %s 2>&1 | FileCheck -check-prefix CHECK-IOS-TVOS %s
+// RUN: %clang -target x86_64-apple-driverkit19.0 -Wincompatible-sysroot -isysroot SDKs/MacOSX10.9.sdk -S -o - %s 2>&1 | FileCheck -check-prefix CHECK-OSX-DRIVERKIT %s
+// RUN: %clang -target x86_64-apple-driverkit19.0 -Wincompatible-sysroot -isysroot SDKs/iPhoneOS9.2.sdk -S -o - %s 2>&1 | FileCheck -check-prefix CHECK-IOS-DRIVERKIT %s
 // RUN: %clang -target x86_64-apple-darwin -Wincompatible-sysroot -isysroot SDKs/iPhoneSimulator9.2.sdk -mios-version-min=9.0 -S -o - %s 2>&1 | FileCheck -check-prefix CHECK-IOS-IOSSIM %s
 // RUN: %clang -target x86_64-apple-darwin -Wno-incompatible-sysroot -isysroot SDKs/MacOSX10.9.sdk -mios-version-min=9.0 -S -o - %s 2>&1 | FileCheck -check-prefix CHECK-OSX-IOS-DISABLED %s
 
@@ -11,5 +13,7 @@
 // CHECK-OSX-IOS: warning: using sysroot for 'MacOSX' but targeting 'iPhone'
 // CHECK-IOS-WATCHOS: warning: using sysroot for 'iPhoneOS' but targeting 'Watch'
 // CHECK-IOS-TVOS: warning: using sysroot for 'iPhoneOS' but targeting 'AppleTV'
+// CHECK-OSX-DRIVERKIT: warning: using sysroot for 'MacOSX' but targeting 'DriverKit'
+// CHECK-IOS-DRIVERKIT: warning: using sysroot for 'iPhoneOS' but targeting 'DriverKit'
 // CHECK-IOS-IOSSIM-NOT: warning: using sysroot for '{{.*}}' but targeting '{{.*}}'
 // CHECK-OSX-IOS-DISABLED-NOT: warning: using sysroot for '{{.*}}' but targeting '{{.*}}'
diff --git a/clang/test/Driver/instrprof-ld.c b/clang/test/Driver/instrprof-ld.c
--- a/clang/test/Driver/instrprof-ld.c
+++ b/clang/test/Driver/instrprof-ld.c
@@ -107,6 +107,14 @@
 // CHECK-WATCHOS-ARMV7: "{{.*}}/Inputs/resource_dir{{/|\\\\}}lib{{/|\\\\}}darwin{{/|\\\\}}libclang_rt.profile_watchos.a"
 //
 // RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
+// RUN:     -target x86_64-apple-driverkit19.0 -arch x86_64 -fprofile-instr-generate -fuse-ld=ld \
+// RUN:     -resource-dir=%S/Inputs/resource_dir \
+// RUN:   | FileCheck --check-prefix=CHECK-DRIVERKIT-X86_64 %s
+//
+// CHECK-DRIVERKIT-X86_64: "{{(.*[^-.0-9A-Z_a-z])?}}ld{{(.exe)?}}"
+// CHECK-DRIVERKIT-X86_64: "{{.*}}/Inputs/resource_dir{{/|\\\\}}lib{{/|\\\\}}darwin{{/|\\\\}}libclang_rt.profile_driverkit.a"
+//
+// RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
 // RUN:     -target i386-pc-win32 -fprofile-instr-generate \
 // RUN:     -resource-dir=%S/Inputs/resource_dir \
 // RUN:   | FileCheck --check-prefix=CHECK-WINDOWS-I386 %s
diff --git a/clang/test/Driver/pic.c b/clang/test/Driver/pic.c
--- a/clang/test/Driver/pic.c
+++ b/clang/test/Driver/pic.c
@@ -231,6 +231,8 @@
 // RUN:   | FileCheck %s --check-prefix=CHECK-NO-STATIC
 // RUN: %clang -c %s -target armv7k-apple-watchos1 -fapple-kext -### 2>&1 \
 // RUN:   | FileCheck %s --check-prefix=CHECK-PIC2
+// RUN: %clang -c %s -target x86_64-apple-driverkit -fapple-kext -### 2>&1 \
+// RUN:   | FileCheck %s --check-prefix=CHECK-PIC2
 // RUN: %clang -c %s -target armv7-apple-ios5 -fapple-kext -### 2>&1 \
 // RUN:   | FileCheck %s --check-prefix=CHECK-NO-PIC
 // RUN: %clang -c %s -target armv7-apple-ios6 -fapple-kext -static -### 2>&1 \
diff --git a/clang/test/Driver/stack-protector.c b/clang/test/Driver/stack-protector.c
--- a/clang/test/Driver/stack-protector.c
+++ b/clang/test/Driver/stack-protector.c
@@ -38,6 +38,8 @@
 // RUN: %clang -target armv7k-apple-watchos2.0 -### %s 2>&1 | FileCheck %s -check-prefix=SSP_WATCHOS
 // RUN: %clang -ffreestanding -target armv7k-apple-watchos2.0 -### %s 2>&1 | FileCheck %s -check-prefix=SSP_WATCHOS
 // SSP_WATCHOS: "-stack-protector" "1"
+// RUN: %clang -target x86_64-apple-driverkit19.0 -### %s 2>&1 | FileCheck %s -check-prefix=SSP_DRIVERKIT
+// SSP_DRIVERKIT: "-stack-protector" "1"
 // RUN: %clang -target arm64-apple-ios8.0.0 -### %s 2>&1 | FileCheck %s -check-prefix=SSP_IOS
 // RUN: %clang -ffreestanding -target arm64-apple-ios8.0.0 -### %s 2>&1 | FileCheck %s -check-prefix=SSP_IOS
 // SSP_IOS: "-stack-protector" "1"
diff --git a/clang/test/Frontend/darwin-version.c b/clang/test/Frontend/darwin-version.c
--- a/clang/test/Frontend/darwin-version.c
+++ b/clang/test/Frontend/darwin-version.c
@@ -51,3 +51,8 @@
 // RUN: grep '__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__' %t | grep '20100' | count 1
 // RUN: not grep '__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__' %t
 // RUN: not grep '__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__' %t
+
+// RUN: %clang_cc1 -triple x86_64-apple-driverkit19.0 -dM -E -o %t %s
+// RUN: grep '__ENVIRONMENT_DRIVERKIT_VERSION_MIN_REQUIRED__' %t | grep '1900' | count 1
+// RUN: not grep '__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__' %t
+// RUN: not grep '__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__' %t
diff --git a/clang/test/Preprocessor/arm-target-features.c b/clang/test/Preprocessor/arm-target-features.c
--- a/clang/test/Preprocessor/arm-target-features.c
+++ b/clang/test/Preprocessor/arm-target-features.c
@@ -834,6 +834,9 @@
 // CHECK-V82A: #define __ARM_FEATURE_QRDMX 1
 // CHECK-V82A: #define __ARM_FP 0xe
 
+// RUN: %clang -target armv7-apple-driverkit21.0 -x c %s -dM -E -o - | FileCheck -match-full-lines --check-prefix=CHECK-DRIVERKIT %s
+// CHECK-DRIVERKIT-NOT: #define __ARM_PCS_VFP 1
+
 // RUN: %clang -target armv8.3a-none-none-eabi -x c -E -dM %s -o - | FileCheck -match-full-lines --check-prefix=CHECK-V83A %s
 // CHECK-V83A: #define __ARM_ARCH 8
 // CHECK-V83A: #define __ARM_ARCH_8_3A__ 1
diff --git a/clang/test/Sema/attr-availability-driverkit.c b/clang/test/Sema/attr-availability-driverkit.c
new file mode 100644
--- /dev/null
+++ b/clang/test/Sema/attr-availability-driverkit.c
@@ -0,0 +1,22 @@
+// RUN: %clang_cc1 "-triple" "x86_64-apple-driverkit20.0" -fsyntax-only -verify %s
+
+void f0(int) __attribute__((availability(driverkit,introduced=19.0,deprecated=20.0))); // expected-note {{'f0' has been explicitly marked deprecated here}}
+void f1(int) __attribute__((availability(driverkit,introduced=20.0)));
+void f2(int) __attribute__((availability(driverkit,introduced=19.0,deprecated=20.0))); // expected-note {{'f2' has been explicitly marked deprecated here}}
+void f3(int) __attribute__((availability(driverkit,introduced=20.0)));
+void f4(int) __attribute__((availability(macosx,introduced=10.1,deprecated=10.3,obsoleted=10.5), availability(driverkit,introduced=19.0,deprecated=19.5,obsoleted=20.0))); // expected-note{{explicitly marked unavailable}}
+
+void f5(int) __attribute__((availability(driverkit,introduced=19.0))) __attribute__((availability(driverkit,deprecated=20.0))); // expected-note {{'f5' has been explicitly marked deprecated here}}
+void f6(int) __attribute__((availability(driverkit,deprecated=20.0))); // expected-note {{'f6' has been explicitly marked deprecated here}}
+void f7(int) __attribute__((availability(driverkit,introduced=19.0)));
+
+void test() {
+  f0(0); // expected-warning{{'f0' is deprecated: first deprecated in DriverKit 20.0}}
+  f1(0);
+  f2(0); // expected-warning{{'f2' is deprecated: first deprecated in DriverKit 20.0}}
+  f3(0);
+  f4(0); // expected-error{{f4' is unavailable: obsoleted in DriverKit 20.0}}
+  f5(0); // expected-warning{{'f5' is deprecated: first deprecated in DriverKit 20.0}}
+  f6(0); // expected-warning{{'f6' is deprecated: first deprecated in DriverKit 20.0}}
+  f7(0);
+}