Index: include/clang/Basic/BuiltinsX86.def
===================================================================
--- include/clang/Basic/BuiltinsX86.def
+++ include/clang/Basic/BuiltinsX86.def
@@ -894,6 +894,9 @@
 BUILTIN(__builtin_ia32_rdtsc, "ULLi", "")
 BUILTIN(__rdtsc, "ULLi", "")
 BUILTIN(__builtin_ia32_rdtscp, "ULLiUi*", "")
+
+TARGET_BUILTIN(__builtin_ia32_rdpid, "Ui", "", "rdpid")
+
 // PKU
 TARGET_BUILTIN(__builtin_ia32_rdpkru, "Ui", "", "pku")
 TARGET_BUILTIN(__builtin_ia32_wrpkru, "vUi", "", "pku")
Index: include/clang/Driver/Options.td
===================================================================
--- include/clang/Driver/Options.td
+++ include/clang/Driver/Options.td
@@ -2562,6 +2562,8 @@
 def mno_prefetchwt1 : Flag<["-"], "mno-prefetchwt1">, Group<m_x86_Features_Group>;
 def mprfchw : Flag<["-"], "mprfchw">, Group<m_x86_Features_Group>;
 def mno_prfchw : Flag<["-"], "mno-prfchw">, Group<m_x86_Features_Group>;
+def mrdpid : Flag<["-"], "mrdpid">, Group<m_x86_Features_Group>;
+def mno_rdpid : Flag<["-"], "mno-rdpid">, Group<m_x86_Features_Group>;
 def mrdrnd : Flag<["-"], "mrdrnd">, Group<m_x86_Features_Group>;
 def mno_rdrnd : Flag<["-"], "mno-rdrnd">, Group<m_x86_Features_Group>;
 def mrtm : Flag<["-"], "mrtm">, Group<m_x86_Features_Group>;
Index: lib/Basic/Targets/X86.h
===================================================================
--- lib/Basic/Targets/X86.h
+++ lib/Basic/Targets/X86.h
@@ -96,6 +96,7 @@
   bool HasCLWB = false;
   bool HasMOVBE = false;
   bool HasPREFETCHWT1 = false;
+  bool HasRDPID = false;
 
   /// \brief Enumeration of all of the X86 CPUs supported by Clang.
   ///
Index: lib/Basic/Targets/X86.cpp
===================================================================
--- lib/Basic/Targets/X86.cpp
+++ lib/Basic/Targets/X86.cpp
@@ -160,6 +160,7 @@
     setFeatureEnabledImpl(Features, "avx512vnni", true);
     setFeatureEnabledImpl(Features, "avx512vbmi2", true);
     setFeatureEnabledImpl(Features, "avx512vpopcntdq", true);
+    setFeatureEnabledImpl(Features, "rdpid", true);
     LLVM_FALLTHROUGH;
   case CK_Cannonlake:
     setFeatureEnabledImpl(Features, "avx512ifma", true);
@@ -784,6 +785,8 @@
       HasPREFETCHWT1 = true;
     } else if (Feature == "+clzero") {
       HasCLZERO = true;
+    } else if (Feature == "+rdpid") {
+      HasRDPID = true;
     }
 
     X86SSEEnum Level = llvm::StringSwitch<X86SSEEnum>(Feature)
@@ -1125,6 +1128,8 @@
     Builder.defineMacro("__PREFETCHWT1__");
   if (HasCLZERO)
     Builder.defineMacro("__CLZERO__");
+  if (HasRDPID)
+    Builder.defineMacro("__RDPID__");
 
   // Each case falls through to the previous one here.
   switch (SSELevel) {
@@ -1253,6 +1258,7 @@
       .Case("popcnt", true)
       .Case("prefetchwt1", true)
       .Case("prfchw", true)
+      .Case("rdpid", true)
       .Case("rdrnd", true)
       .Case("rdseed", true)
       .Case("rtm", true)
@@ -1324,6 +1330,7 @@
       .Case("popcnt", HasPOPCNT)
       .Case("prefetchwt1", HasPREFETCHWT1)
       .Case("prfchw", HasPRFCHW)
+      .Case("rdpid", HasRDPID)
       .Case("rdrnd", HasRDRND)
       .Case("rdseed", HasRDSEED)
       .Case("rtm", HasRTM)
Index: lib/Headers/immintrin.h
===================================================================
--- lib/Headers/immintrin.h
+++ lib/Headers/immintrin.h
@@ -247,6 +247,18 @@
 #include <gfniintrin.h>
 #endif
 
+#if !defined(_MSC_VER) || __has_feature(modules) || defined(__RDPID__)
+/// \brief Returns the value of the IA32_TSC_AUX MSR (0xc0000103).
+///
+/// \headerfile <immintrin.h>
+///
+/// This intrinsic corresponds to the <c> RDPID </c> instruction.
+static __inline__ unsigned int __attribute__((__always_inline__, __nodebug__, __target__("rdpid")))
+_rdpid_u32(void) {
+  return __builtin_ia32_rdpid();
+}
+#endif // __RDPID__
+
 #if !defined(_MSC_VER) || __has_feature(modules) || defined(__RDRND__)
 static __inline__ int __attribute__((__always_inline__, __nodebug__, __target__("rdrnd")))
 _rdrand16_step(unsigned short *__p)
Index: test/CodeGen/rdpid-builtins.c
===================================================================
--- /dev/null
+++ test/CodeGen/rdpid-builtins.c
@@ -0,0 +1,10 @@
+// RUN: %clang_cc1 -ffreestanding -triple x86_64-unknown-unknown -target-feature +rdpid -emit-llvm -o - %s | FileCheck %s
+
+
+#include <x86intrin.h>
+
+unsigned int test_rdpid_u32(void) {
+// CHECK-LABEL: @test_rdpid_u32
+// CHECK: call i32 @llvm.x86.rdpid
+  return _rdpid_u32();
+}
Index: test/Driver/x86-target-features.c
===================================================================
--- test/Driver/x86-target-features.c
+++ test/Driver/x86-target-features.c
@@ -125,3 +125,7 @@
 // VBMI2: "-target-feature" "+avx512vbmi2"
 // NO-VBMI2: "-target-feature" "-avx512vbmi2"
 
+// RUN: %clang -target i386-unknown-linux-gnu -march=i386 -mrdpid %s -### -o %t.o 2>&1 | FileCheck -check-prefix=RDPID %s
+// RUN: %clang -target i386-unknown-linux-gnu -march=i386 -mno-rdpid %s -### -o %t.o 2>&1 | FileCheck -check-prefix=NO-RDPID %s
+// RDPID: "-target-feature" "+rdpid"
+// NO-RDPID: "-target-feature" "-rdpid"
Index: test/Preprocessor/predefined-arch-macros.c
===================================================================
--- test/Preprocessor/predefined-arch-macros.c
+++ test/Preprocessor/predefined-arch-macros.c
@@ -1086,6 +1086,7 @@
 // CHECK_ICL_M32: #define __PKU__ 1
 // CHECK_ICL_M32: #define __POPCNT__ 1
 // CHECK_ICL_M32: #define __PRFCHW__ 1
+// CHECK_ICL_M32: #define __RDPID__ 1
 // CHECK_ICL_M32: #define __RDRND__ 1
 // CHECK_ICL_M32: #define __RDSEED__ 1
 // CHECK_ICL_M32: #define __RTM__ 1
@@ -1141,6 +1142,7 @@
 // CHECK_ICL_M64: #define __PKU__ 1
 // CHECK_ICL_M64: #define __POPCNT__ 1
 // CHECK_ICL_M64: #define __PRFCHW__ 1
+// CHECK_ICL_M64: #define __RDPID__ 1
 // CHECK_ICL_M64: #define __RDRND__ 1
 // CHECK_ICL_M64: #define __RDSEED__ 1
 // CHECK_ICL_M64: #define __RTM__ 1
Index: test/Preprocessor/x86_target_features.c
===================================================================
--- test/Preprocessor/x86_target_features.c
+++ test/Preprocessor/x86_target_features.c
@@ -436,3 +436,6 @@
 // VPCLMULQDQNOPCLMUL-NOT: #define __PCLMUL__ 1
 // VPCLMULQDQNOPCLMUL-NOT: #define __VPCLMULQDQ__ 1
 
+// RUN: %clang -target i386-unknown-unknown -march=atom -mrdpid -x c -E -dM -o - %s | FileCheck -match-full-lines --check-prefix=RDPID %s
+
+// RDPID: #define __RDPID__ 1