Index: lib/Driver/Tools.cpp
===================================================================
--- lib/Driver/Tools.cpp
+++ lib/Driver/Tools.cpp
@@ -574,23 +574,47 @@
     D.Diag(diag::err_drv_clang_unsupported) << A->getAsString(Args);
 }
 
+// Decode ARM features from string like +[no]featureA+[no]featureB+...
+static bool DecodeARMFeatures(const Driver &D, StringRef text,
+                              std::vector<const char *> &Features) {
+  SmallVector<StringRef, 8> Split;
+  text.split(Split, StringRef("+"), -1, false);
+
+  for (StringRef Feature : Split) {
+    const char *FeatureName = llvm::ARM::getArchExtFeature(Feature);
+    if (FeatureName)
+      Features.push_back(FeatureName);
+    else
+      return false;
+  }
+  return true;
+}
+
 // Check if -march is valid by checking if it can be canonicalised and parsed.
 // getARMArch is used here instead of just checking the -march value in order
 // to handle -march=native correctly.
 static void checkARMArchName(const Driver &D, const Arg *A, const ArgList &Args,
                              llvm::StringRef ArchName,
+                             std::vector<const char *> &Features,
                              const llvm::Triple &Triple) {
+  std::pair<StringRef, StringRef> Split = ArchName.split("+");
+
   std::string MArch = arm::getARMArch(ArchName, Triple);
-  if (llvm::ARM::parseArch(MArch) == llvm::ARM::AK_INVALID)
+  if (llvm::ARM::parseArch(MArch) == llvm::ARM::AK_INVALID ||
+      (Split.second.size() && !DecodeARMFeatures(D, Split.second, Features)))
     D.Diag(diag::err_drv_clang_unsupported) << A->getAsString(Args);
 }
 
 // Check -mcpu=. Needs ArchName to handle -mcpu=generic.
 static void checkARMCPUName(const Driver &D, const Arg *A, const ArgList &Args,
                             llvm::StringRef CPUName, llvm::StringRef ArchName,
+                            std::vector<const char *> &Features,
                             const llvm::Triple &Triple) {
+  std::pair<StringRef, StringRef> Split = CPUName.split("+");
+
   std::string CPU = arm::getARMTargetCPU(CPUName, ArchName, Triple);
-  if (arm::getLLVMArchSuffixForARM(CPU, ArchName, Triple).empty())
+  if (arm::getLLVMArchSuffixForARM(CPU, ArchName, Triple).empty() ||
+      (Split.second.size() && !DecodeARMFeatures(D, Split.second, Features)))
     D.Diag(diag::err_drv_clang_unsupported) << A->getAsString(Args);
 }
 
@@ -756,12 +780,12 @@
       D.Diag(clang::diag::warn_drv_unused_argument)
           << ArchArg->getAsString(Args);
     ArchName = StringRef(WaArch->getValue()).substr(7);
-    checkARMArchName(D, WaArch, Args, ArchName, Triple);
+    checkARMArchName(D, WaArch, Args, ArchName, Features, Triple);
     // FIXME: Set Arch.
     D.Diag(clang::diag::warn_drv_unused_argument) << WaArch->getAsString(Args);
   } else if (ArchArg) {
     ArchName = ArchArg->getValue();
-    checkARMArchName(D, ArchArg, Args, ArchName, Triple);
+    checkARMArchName(D, ArchArg, Args, ArchName, Features, Triple);
   }
 
   // Check -mcpu. ClangAs gives preference to -Wa,-mcpu=.
@@ -772,10 +796,10 @@
       D.Diag(clang::diag::warn_drv_unused_argument)
           << CPUArg->getAsString(Args);
     CPUName = StringRef(WaCPU->getValue()).substr(6);
-    checkARMCPUName(D, WaCPU, Args, CPUName, ArchName, Triple);
+    checkARMCPUName(D, WaCPU, Args, CPUName, ArchName, Features, Triple);
   } else if (CPUArg) {
     CPUName = CPUArg->getValue();
-    checkARMCPUName(D, CPUArg, Args, CPUName, ArchName, Triple);
+    checkARMCPUName(D, CPUArg, Args, CPUName, ArchName, Features, Triple);
   }
 
   // Add CPU features for generic CPUs
@@ -6241,7 +6265,7 @@
     MArch = Arch;
   else
     MArch = Triple.getArchName();
-  MArch = StringRef(MArch).lower();
+  MArch = StringRef(MArch).split("+").first.lower();
 
   // Handle -march=native.
   if (MArch == "native") {
@@ -6280,7 +6304,7 @@
   // FIXME: Warn on inconsistent use of -mcpu and -march.
   // If we have -mcpu=, use that.
   if (!CPU.empty()) {
-    std::string MCPU = StringRef(CPU).lower();
+    std::string MCPU = StringRef(CPU).split("+").first.lower();
     // Handle -mcpu=native.
     if (MCPU == "native")
       return llvm::sys::getHostCPUName();
Index: test/Driver/arm-features.c
===================================================================
--- /dev/null
+++ test/Driver/arm-features.c
@@ -0,0 +1,7 @@
+// RUN: %clang -target arm -mcpu=generic+crc -march=armv8a -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-CRC %s
+// RUN: %clang -target arm -mcpu=generic -march=armv8a+crc -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-CRC %s
+// CHECK-CRC: "-cc1"{{.*}} "-triple" "armv8-{{.*}} "-target-cpu" "generic"{{.*}} "-target-feature" "+crc"
+
+// RUN: %clang -target arm -mcpu=generic+nocrc -march=armv8a -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-NOCRC %s
+// RUN: %clang -target arm -mcpu=generic -march=armv8a+nocrc -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-NOCRC %s
+// CHECK-NOCRC: "-cc1"{{.*}} "-triple" "armv8-{{.*}} "-target-cpu" "generic"{{.*}} "-target-feature" "-crc"