diff --git a/llvm/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp b/llvm/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp
--- a/llvm/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp
+++ b/llvm/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp
@@ -970,11 +970,15 @@
   bool isMOVZMovAlias() const {
     if (!isImm()) return false;
 
-    const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(getImm());
-    if (!CE) return false;
-    uint64_t Value = CE->getValue();
+    const MCExpr *E = getImm();
+    if (const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(E)) {
+      uint64_t Value = CE->getValue();
 
-    return AArch64_AM::isMOVZMovAlias(Value, Shift, RegWidth);
+      return AArch64_AM::isMOVZMovAlias(Value, Shift, RegWidth);
+    }
+    // For expressions, only support the case of Shift being 0 as the result is
+    // unknown at this point.
+    return !Shift && E;
   }
 
   template<int RegWidth, int Shift>
@@ -1774,9 +1778,14 @@
   void addMOVZMovAliasOperands(MCInst &Inst, unsigned N) const {
     assert(N == 1 && "Invalid number of operands!");
 
-    const MCConstantExpr *CE = cast<MCConstantExpr>(getImm());
-    uint64_t Value = CE->getValue();
-    Inst.addOperand(MCOperand::createImm((Value >> Shift) & 0xffff));
+    const MCExpr *E = getImm();
+    if (const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(getImm())) {
+      uint64_t Value = CE->getValue();
+      Inst.addOperand(MCOperand::createImm((Value >> Shift) & 0xffff));
+    } else {
+      assert(!Shift && "Do not support shifted expressions as an operand!");
+      addExpr(Inst, AArch64MCExpr::create(E, AArch64MCExpr::VK_ABS_G0_S, Ctx));
+    }
   }
 
   template<int Shift>
diff --git a/llvm/test/MC/AArch64/basic-a64-diagnostics.s b/llvm/test/MC/AArch64/basic-a64-diagnostics.s
--- a/llvm/test/MC/AArch64/basic-a64-diagnostics.s
+++ b/llvm/test/MC/AArch64/basic-a64-diagnostics.s
@@ -167,9 +167,9 @@
         // MOV alias should not accept any fiddling
         mov x2, xsp, #123
         mov wsp, w27, #0xfff, lsl #12
-// CHECK-ERROR: error: expected compatible register or logical immediate
+// CHECK-ERROR: error: invalid operand for instruction
 // CHECK-ERROR-NEXT:         mov x2, xsp, #123
-// CHECK-ERROR-NEXT:                 ^
+// CHECK-ERROR-NEXT:                      ^
 // CHECK-ERROR-NEXT: error: invalid operand for instruction
 // CHECK-ERROR-NEXT:         mov wsp, w27, #0xfff, lsl #12
 // CHECK-ERROR-NEXT:                       ^
diff --git a/llvm/test/MC/AArch64/mov-expression-as-immediate.s b/llvm/test/MC/AArch64/mov-expression-as-immediate.s
new file mode 100644
--- /dev/null
+++ b/llvm/test/MC/AArch64/mov-expression-as-immediate.s
@@ -0,0 +1,11 @@
+// RUN: llvm-mc -triple aarch64-none-linux-gnu %s -filetype=obj -o %t | llvm-objdump -d %t | FileCheck %s
+
+0:
+.skip 4
+1:
+mov x0, 1b - 0b
+// CHECK: mov x0, #4
+mov x0, 0b - 1b
+// CHECK: mov x0, #-4
+mov x0, 0b - 0b
+// CHECK: mov x0, #0
diff --git a/llvm/test/MC/AArch64/mov-invalid-expression-as-immediate.s b/llvm/test/MC/AArch64/mov-invalid-expression-as-immediate.s
new file mode 100644
--- /dev/null
+++ b/llvm/test/MC/AArch64/mov-invalid-expression-as-immediate.s
@@ -0,0 +1,9 @@
+// RUN: not llvm-mc -triple aarch64-none-linux-gnu %s -filetype=obj -o /dev/null 2>&1 | FileCheck %s
+
+0:
+.skip 0x10000
+1:
+mov x0, 1b - 0b
+// CHECK: error: fixup value out of range
+// CHECK: mov x0, 1b - 0b
+// CHECK: ^