diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -26761,6 +26761,19 @@
                                              getPointerTy(DAG.getDataLayout())),
                        Op.getOperand(1), ShAmt);
   }
+  case Intrinsic::thread_pointer: {
+    if (Subtarget.isTargetELF()) {
+      SDLoc dl(Op);
+      EVT PtrVT = getPointerTy(DAG.getDataLayout());
+      // Get the Thread Pointer, which is %gs:0 (32-bit) or %fs:0 (64-bit).
+      Value *Ptr = Constant::getNullValue(Type::getInt8PtrTy(
+          *DAG.getContext(), Subtarget.is64Bit() ? X86AS::FS : X86AS::GS));
+      return DAG.getLoad(PtrVT, dl, DAG.getEntryNode(),
+                         DAG.getIntPtrConstant(0, dl), MachinePointerInfo(Ptr));
+    }
+    report_fatal_error(
+        "Target OS doesn't support __builtin_thread_pointer() yet.");
+  }
   }
 }
 
diff --git a/llvm/test/CodeGen/X86/thread_pointer-error.ll b/llvm/test/CodeGen/X86/thread_pointer-error.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/X86/thread_pointer-error.ll
@@ -0,0 +1,16 @@
+; FIXME: Targets below should support this builtin after they document the thread pointer for X86.
+; CHECK-ERROR: LLVM ERROR: Target OS doesn't support __builtin_thread_pointer() yet.
+
+; RUN: not --crash llc < %s -o /dev/null -mtriple=i686-pc-win32 2>&1 | FileCheck %s --check-prefix=CHECK-ERROR
+; RUN: not --crash llc < %s -o /dev/null -mtriple=x86_64-pc-win32 2>&1 | FileCheck %s --check-prefix=CHECK-ERROR
+; RUN: not --crash llc < %s -o /dev/null -mtriple=i686-pc-windows-gnu 2>&1 | FileCheck %s --check-prefix=CHECK-ERROR
+; RUN: not --crash llc < %s -o /dev/null -mtriple=x86_64-pc-windows-gnu 2>&1 | FileCheck %s --check-prefix=CHECK-ERROR
+; RUN: not --crash llc < %s -o /dev/null -mtriple=i686-apple-darwin 2>&1 | FileCheck %s --check-prefix=CHECK-ERROR
+; RUN: not --crash llc < %s -o /dev/null -mtriple=x86_64-pc-apple-darwin 2>&1 | FileCheck %s --check-prefix=CHECK-ERROR
+
+declare i8* @llvm.thread.pointer()
+
+define i8* @thread_pointer() nounwind {
+  %1 = tail call i8* @llvm.thread.pointer()
+  ret i8* %1
+}
diff --git a/llvm/test/CodeGen/X86/thread_pointer.ll b/llvm/test/CodeGen/X86/thread_pointer.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/X86/thread_pointer.ll
@@ -0,0 +1,51 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -mtriple=x86_64-linux-gnu | FileCheck %s --check-prefix=X64
+; RUN: llc < %s -mtriple=x86_64-linux-gnux32 | FileCheck %s --check-prefix=X32
+; RUN: llc < %s -mtriple=i386-linux-gnu | FileCheck %s --check-prefix=X86
+
+declare i8* @llvm.thread.pointer()
+
+define i8* @thread_pointer() nounwind {
+; X64-LABEL: thread_pointer:
+; X64:       # %bb.0:
+; X64-NEXT:    movq %fs:0, %rax
+; X64-NEXT:    retq
+;
+; X32-LABEL: thread_pointer:
+; X32:       # %bb.0:
+; X32-NEXT:    movl %fs:0, %eax
+; X32-NEXT:    retq
+;
+; X86-LABEL: thread_pointer:
+; X86:       # %bb.0:
+; X86-NEXT:    movl %gs:0, %eax
+; X86-NEXT:    retl
+  %1 = tail call i8* @llvm.thread.pointer()
+  ret i8* %1
+}
+
+define i32 @thread_pointer2(i32 %i) nounwind {
+; X64-LABEL: thread_pointer2:
+; X64:       # %bb.0: # %entry
+; X64-NEXT:    movslq %edi, %rax
+; X64-NEXT:    movl %fs:(,%rax,4), %eax
+; X64-NEXT:    retq
+;
+; X32-LABEL: thread_pointer2:
+; X32:       # %bb.0: # %entry
+; X32-NEXT:    movl %fs:0, %eax
+; X32-NEXT:    movl (%eax,%edi,4), %eax
+; X32-NEXT:    retq
+;
+; X86-LABEL: thread_pointer2:
+; X86:       # %bb.0: # %entry
+; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    movl %gs:(,%eax,4), %eax
+; X86-NEXT:    retl
+entry:
+  %0 = tail call i8* @llvm.thread.pointer()
+  %1 = bitcast i8* %0 to i32*
+  %arrayidx = getelementptr inbounds i32, i32* %1, i32 %i
+  %2 = load i32, i32* %arrayidx, align 4
+  ret i32 %2
+}