Index: include/llvm/DebugInfo/DWARF/DWARFDie.h
===================================================================
--- include/llvm/DebugInfo/DWARF/DWARFDie.h
+++ include/llvm/DebugInfo/DWARF/DWARFDie.h
@@ -282,9 +282,21 @@
   /// This is a utility function that checks for either the DW_AT_rnglists_base
   /// or DW_AT_GNU_ranges_base attribute.
   ///
-  /// \returns anm optional absolute section offset value for the attribute.
+  /// \returns an optional absolute section offset value for the attribute.
   Optional<uint64_t> getRangesBaseAttribute() const;
   
+  /// Get the DW_AT_high_pc attribute value as an address
+  ///
+  /// In DWARF version 4 and later the high PC can be encoded as an offset from
+  /// the DW_AT_low_pc. This function takes care of extracting the value as an
+  /// address or offset and adds it to the low PC if needed and returns the
+  /// value as an optional in case the DIE doesn't have a DW_AT_high_pc
+  /// attribute.
+  ///
+  /// \param LowPC the low PC that might be needed to calculate the high PC.
+  /// \returns an optional address value for the attribute.
+  Optional<uint64_t> getHighPC(uint64_t LowPC) const;
+
   /// Retrieves DW_AT_low_pc and DW_AT_high_pc from CU.
   /// Returns true if both attributes are present.
   bool getLowAndHighPC(uint64_t &LowPC, uint64_t &HighPC) const;
Index: lib/DebugInfo/DWARF/DWARFDie.cpp
===================================================================
--- lib/DebugInfo/DWARF/DWARFDie.cpp
+++ lib/DebugInfo/DWARF/DWARFDie.cpp
@@ -245,21 +245,30 @@
   return getAttributeValueAsSectionOffset(DW_AT_GNU_ranges_base);
 }
 
+Optional<uint64_t> DWARFDie::getHighPC(uint64_t LowPC) const {
+  if (auto FormValue = getAttributeValue(DW_AT_high_pc)) {
+    if (auto Address = FormValue->getAsAddress()) {
+      // High PC is an address.
+      return Address;
+    }
+    if (auto Offset = FormValue->getAsUnsignedConstant()) {
+      // High PC is an offset from LowPC.
+      return LowPC + *Offset;
+    }
+  }
+  return None;
+}
+
 bool DWARFDie::getLowAndHighPC(uint64_t &LowPC, uint64_t &HighPC) const {
-  if (auto LowPCVal = getAttributeValueAsAddress(DW_AT_low_pc))
-    LowPC = *LowPCVal;
-  else
+  auto LowPcAddr = getAttributeValueAsAddress(DW_AT_low_pc);
+  if (!LowPcAddr)
     return false;
-
-  if (auto HighPCVal = getAttributeValueAsAddress(DW_AT_high_pc)) {
-    // High PC is an address.
-    HighPC = *HighPCVal;
-  } else if (auto Offset = getAttributeValueAsUnsignedConstant(DW_AT_high_pc)) {
-    // High PC is an offset from LowPC.
-    HighPC = LowPC + *Offset;
-  } else
-    return false;
-  return true;
+  LowPC = *LowPcAddr;
+  if (auto HighPcAddr = getHighPC(LowPC)) {
+    HighPC = *HighPcAddr;
+    return true;
+  }
+  return false;
 }
 
 DWARFAddressRangesVector
Index: tools/dsymutil/DwarfLinker.cpp
===================================================================
--- tools/dsymutil/DwarfLinker.cpp
+++ tools/dsymutil/DwarfLinker.cpp
@@ -2134,24 +2134,16 @@
 
   Flags |= TF_Keep;
 
-  Optional<DWARFFormValue> HighPcValue;
-  if (!(HighPcValue = DIE.getAttributeValue(dwarf::DW_AT_high_pc))) {
+  Optional<uint64_t> HighPc = DIE.getHighPC(*LowPc);
+  if (!HighPc) {
     reportWarning("Function without high_pc. Range will be discarded.\n",
                   &DIE);
     return Flags;
   }
 
-  uint64_t HighPc;
-  if (HighPcValue->isFormClass(DWARFFormValue::FC_Address)) {
-    HighPc = *HighPcValue->getAsAddress();
-  } else {
-    assert(HighPcValue->isFormClass(DWARFFormValue::FC_Constant));
-    HighPc = *LowPc + *HighPcValue->getAsUnsignedConstant();
-  }
-
   // Replace the debug map range with a more accurate one.
-  Ranges[*LowPc] = std::make_pair(HighPc, MyInfo.AddrAdjust);
-  Unit.addFunctionRange(*LowPc, HighPc, MyInfo.AddrAdjust);
+  Ranges[*LowPc] = std::make_pair(*HighPc, MyInfo.AddrAdjust);
+  Unit.addFunctionRange(*LowPc, *HighPc, MyInfo.AddrAdjust);
   return Flags;
 }