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 +970,18 @@
   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 = dyn_cast<MCExpr>(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);
+    }
+    if (const MCBinaryExpr *BE = dyn_cast<MCBinaryExpr>(E)) {
+      return (BE->getOpcode() == MCBinaryExpr::Opcode::Sub &&
+              BE->getLHS()->getKind() == MCExpr::ExprKind::SymbolRef &&
+              BE->getLHS()->getKind() == MCExpr::ExprKind::SymbolRef);
+    }
+    return false;
   }
 
   template<int RegWidth, int Shift>
@@ -1774,9 +1781,14 @@
   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 MCConstantExpr *CE = dyn_cast<MCConstantExpr>(getImm());
+    if (CE) {
+      uint64_t Value = CE->getValue();
+      Inst.addOperand(MCOperand::createImm((Value >> Shift) & 0xffff));
+    } else {
+      addExpr(Inst, getImm());
+      Inst.addOperand(MCOperand::createImm(0));
+    }
   }
 
   template<int Shift>
diff --git a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64AsmBackend.cpp b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64AsmBackend.cpp
--- a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64AsmBackend.cpp
+++ b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64AsmBackend.cpp
@@ -239,8 +239,18 @@
       Ctx.reportError(Fixup.getLoc(), "fixup must be 16-byte aligned");
     return Value >> 4;
   case AArch64::fixup_aarch64_movw: {
+    if (!IsResolved) {
+      // FIXME: Figure out when this can actually happen, and verify our
+      // behavior.
+      Ctx.reportError(Fixup.getLoc(), "unresolved movw fixup not yet "
+                                      "implemented");
+      return Value;
+    }
+    // Results of label arithmetic operaitons
     AArch64MCExpr::VariantKind RefKind =
         static_cast<AArch64MCExpr::VariantKind>(Target.getRefKind());
+    if (!RefKind)
+      return Value;
     if (AArch64MCExpr::getSymbolLoc(RefKind) != AArch64MCExpr::VK_ABS &&
         AArch64MCExpr::getSymbolLoc(RefKind) != AArch64MCExpr::VK_SABS) {
       // VK_GOTTPREL, VK_TPREL, VK_DTPREL are movw fixups, but they can't
@@ -251,13 +261,6 @@
       return Value;
     }
 
-    if (!IsResolved) {
-      // FIXME: Figure out when this can actually happen, and verify our
-      // behavior.
-      Ctx.reportError(Fixup.getLoc(), "unresolved movw fixup not yet "
-                                      "implemented");
-      return Value;
-    }
 
     if (AArch64MCExpr::getSymbolLoc(RefKind) == AArch64MCExpr::VK_SABS) {
       switch (AArch64MCExpr::getAddressFrag(RefKind)) {
diff --git a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCCodeEmitter.cpp b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCCodeEmitter.cpp
--- a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCCodeEmitter.cpp
+++ b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCCodeEmitter.cpp
@@ -569,21 +569,30 @@
   if (UImm16MO.isImm())
     return EncodedValue;
 
-  const AArch64MCExpr *A64E = cast<AArch64MCExpr>(UImm16MO.getExpr());
-  switch (A64E->getKind()) {
-  case AArch64MCExpr::VK_DTPREL_G2:
-  case AArch64MCExpr::VK_DTPREL_G1:
-  case AArch64MCExpr::VK_DTPREL_G0:
-  case AArch64MCExpr::VK_GOTTPREL_G1:
-  case AArch64MCExpr::VK_TPREL_G2:
-  case AArch64MCExpr::VK_TPREL_G1:
-  case AArch64MCExpr::VK_TPREL_G0:
-    return EncodedValue & ~(1u << 30);
-  default:
-    // Nothing to do for an unsigned fixup.
-    return EncodedValue;
+  const MCExpr *E = UImm16MO.getExpr();
+  if (const AArch64MCExpr *A64E = dyn_cast<AArch64MCExpr>(E)) {
+    switch (A64E->getKind()) {
+    case AArch64MCExpr::VK_DTPREL_G2:
+    case AArch64MCExpr::VK_DTPREL_G1:
+    case AArch64MCExpr::VK_DTPREL_G0:
+    case AArch64MCExpr::VK_GOTTPREL_G1:
+    case AArch64MCExpr::VK_TPREL_G2:
+    case AArch64MCExpr::VK_TPREL_G1:
+    case AArch64MCExpr::VK_TPREL_G0:
+      return EncodedValue & ~(1u << 30);
+    default:
+      // Nothing to do for an unsigned fixup.
+      return EncodedValue;
+    }
   }
 
+  if (const MCBinaryExpr *BE = dyn_cast<MCBinaryExpr>(E)) {
+    if (BE->getOpcode() == MCBinaryExpr::Opcode::Sub &&
+        BE->getLHS()->getKind() == MCExpr::ExprKind::SymbolRef &&
+        BE->getLHS()->getKind() == MCExpr::ExprKind::SymbolRef) {
+      return EncodedValue;
+    }
+  }
 
   return EncodedValue & ~(1u << 30);
 }