diff --git a/clang/test/CodeGen/ms-inline-asm-64.c b/clang/test/CodeGen/ms-inline-asm-64.c
--- a/clang/test/CodeGen/ms-inline-asm-64.c
+++ b/clang/test/CodeGen/ms-inline-asm-64.c
@@ -72,3 +72,10 @@
   // CHECK-SAME: jmp ${1:P}
   // CHECK-SAME: "*m,*m,~{dirflag},~{fpsr},~{flags}"(ptr elementtype(void (...)) @bar, ptr elementtype(void (...)) @bar)
 }
+
+void t47(void) {
+  // CHECK-LABEL: define{{.*}} void @t47
+  int arr[1000];
+  __asm movdir64b rax, zmmword ptr [arr]
+  // CHECK: call void asm sideeffect inteldialect "movdir64b rax, zmmword ptr $0", "*m,~{dirflag},~{fpsr},~{flags}"(ptr elementtype([1000 x i32]) %arr)
+}
diff --git a/clang/test/CodeGen/ms-inline-asm.c b/clang/test/CodeGen/ms-inline-asm.c
--- a/clang/test/CodeGen/ms-inline-asm.c
+++ b/clang/test/CodeGen/ms-inline-asm.c
@@ -675,6 +675,13 @@
   // CHECK: call void asm sideeffect inteldialect "add eax, [eax + $$-128]", "~{eax},~{flags},~{dirflag},~{fpsr},~{flags}"()
 }
 
+void t47(void) {
+  // CHECK-LABEL: define{{.*}} void @t47
+  int arr[1000];
+  __asm movdir64b eax, zmmword ptr [arr]
+  // CHECK: call void asm sideeffect inteldialect "movdir64b eax, zmmword ptr $0", "*m,~{dirflag},~{fpsr},~{flags}"(ptr elementtype([1000 x i32]) %arr)
+}
+
 void dot_operator(void){
   // CHECK-LABEL: define{{.*}} void @dot_operator
 	__asm { mov eax, 3[ebx]A.b}
diff --git a/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp b/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp
--- a/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp
+++ b/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp
@@ -1776,10 +1776,6 @@
                                              BaseReg && IndexReg));
     return false;
   }
-  // Otherwise, we set the base register to a non-zero value
-  // if we don't know the actual value at this time.  This is necessary to
-  // get the matching correct in some cases.
-  BaseReg = BaseReg ? BaseReg : 1;
   Operands.push_back(X86Operand::CreateMem(
       getPointerWidth(), SegReg, Disp, BaseReg, IndexReg, Scale, Start, End,
       Size,
diff --git a/llvm/test/CodeGen/X86/movdir64b-inline-asm-x86_64.ll b/llvm/test/CodeGen/X86/movdir64b-inline-asm-x86_64.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/X86/movdir64b-inline-asm-x86_64.ll
@@ -0,0 +1,21 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 2
+; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mattr=+movdir64b | FileCheck %s --check-prefix=X64
+
+define void @test_movdir64b() {
+; X64-LABEL: test_movdir64b:
+; X64:       # %bb.0: # %entry
+; X64-NEXT:    subq $3880, %rsp # imm = 0xF28
+; X64-NEXT:    .cfi_def_cfa_offset 3888
+; X64-NEXT:    #APP
+; X64-EMPTY:
+; X64-NEXT:    movdir64b -{{[0-9]+}}(%rsp), %rax
+; X64-EMPTY:
+; X64-NEXT:    #NO_APP
+; X64-NEXT:    addq $3880, %rsp # imm = 0xF28
+; X64-NEXT:    .cfi_def_cfa_offset 8
+; X64-NEXT:    retq
+entry:
+  %arr = alloca [1000 x i32], align 16
+  call void asm sideeffect inteldialect "movdir64b rax, zmmword ptr $0", "*m,~{dirflag},~{fpsr},~{flags}"(ptr elementtype([1000 x i32]) %arr)
+  ret void
+}
diff --git a/llvm/test/CodeGen/X86/movdir64b-inline-asm.ll b/llvm/test/CodeGen/X86/movdir64b-inline-asm.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/X86/movdir64b-inline-asm.ll
@@ -0,0 +1,21 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 2
+; RUN: llc < %s -mtriple=i686-unknown-unknown -mattr=+movdir64b | FileCheck %s --check-prefix=X86
+
+define void @test_movdir64b() {
+; X86-LABEL: test_movdir64b:
+; X86:       # %bb.0: # %entry
+; X86-NEXT:    subl $4000, %esp # imm = 0xFA0
+; X86-NEXT:    .cfi_def_cfa_offset 4004
+; X86-NEXT:    #APP
+; X86-EMPTY:
+; X86-NEXT:    movdir64b (%esp), %eax
+; X86-EMPTY:
+; X86-NEXT:    #NO_APP
+; X86-NEXT:    addl $4000, %esp # imm = 0xFA0
+; X86-NEXT:    .cfi_def_cfa_offset 4
+; X86-NEXT:    retl
+entry:
+  %arr = alloca [1000 x i32], align 4
+  call void asm sideeffect inteldialect "movdir64b eax, zmmword ptr $0", "*m,~{dirflag},~{fpsr},~{flags}"(ptr elementtype([1000 x i32]) %arr)
+  ret void
+}