diff --git a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCAsmInfo.cpp b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCAsmInfo.cpp
--- a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCAsmInfo.cpp
+++ b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCAsmInfo.cpp
@@ -46,6 +46,7 @@
   UsesELFSectionDirectiveForBSS = true;
   SupportsDebugInformation = true;
   UseDataRegionDirectives = true;
+  DwarfFDESymbolsUseAbsDiff = true;
 
   ExceptionsType = ExceptionHandling::DwarfCFI;
 }
diff --git a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MachObjectWriter.cpp b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MachObjectWriter.cpp
--- a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MachObjectWriter.cpp
+++ b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MachObjectWriter.cpp
@@ -320,9 +320,33 @@
     }
 
     const MCSymbol *Base = Asm.getAtom(*Symbol);
-    // If the symbol is a variable it can either be in a section and
-    // we have a base or it is absolute and should have been expanded.
-    assert(!Symbol->isVariable() || Base);
+
+    // If the symbol is a variable and we weren't able to get a Base for it
+    // (i.e., it's not in the symbol table associated with a section) resolve
+    // the relocation based its expansion instead.
+    if (Symbol->isVariable() && !Base) {
+      // If the evaluation is an absolute value, just use that directly
+      // to keep things easy.
+      int64_t Res;
+      if (Symbol->getVariableValue()->evaluateAsAbsolute(
+              Res, Layout, Writer->getSectionAddressMap())) {
+        FixedValue = Res;
+        return;
+      }
+
+      // FIXME: Will the Target we already have ever have any data in it
+      // we need to preserve and merge with the new Target? How about
+      // the FixedValue?
+      if (!Symbol->getVariableValue()->evaluateAsRelocatable(Target, &Layout,
+                                                             &Fixup)) {
+        Asm.getContext().reportError(Fixup.getLoc(),
+                                     "unable to resolve variable '" +
+                                         Symbol->getName() + "'");
+        return;
+      }
+      return recordRelocation(Writer, Asm, Layout, Fragment, Fixup, Target,
+                              FixedValue);
+    }
 
     // Relocations inside debug sections always use local relocations when
     // possible. This seems to be done because the debugger doesn't fully
@@ -361,8 +385,19 @@
         Value -= Writer->getFragmentAddress(Fragment, Layout) +
                  Fixup.getOffset() + (1ULL << Log2Size);
     } else {
-      llvm_unreachable(
-          "This constant variable should have been expanded during evaluation");
+      // Resolve constant variables.
+      if (Symbol->isVariable()) {
+        int64_t Res;
+        if (Symbol->getVariableValue()->evaluateAsAbsolute(
+                Res, Layout, Writer->getSectionAddressMap())) {
+          FixedValue = Res;
+          return;
+        }
+      }
+      Asm.getContext().reportError(Fixup.getLoc(),
+                                  "unsupported relocation of variable '" +
+                                      Symbol->getName() + "'");
+      return;
     }
   }