diff --git a/include/llvm/DebugInfo/DWARFFormValue.h b/include/llvm/DebugInfo/DWARFFormValue.h
index 162b1deec0f..5bb6d1b9ddb 100644
--- a/include/llvm/DebugInfo/DWARFFormValue.h
+++ b/include/llvm/DebugInfo/DWARFFormValue.h
@@ -57,6 +57,13 @@ public:
   bool isFormClass(FormClass FC) const;
 
   void dump(raw_ostream &OS, const DWARFUnit *U) const;
+
+  /// \brief extracts a value in data at offset *offset_ptr.
+  ///
+  /// The passed DWARFUnit is allowed to be nullptr, in which
+  /// case no relocation processing will be performed and some
+  /// kind of forms that depend on Unit information are disallowed.
+  /// \returns wether the extraction succeeded.
   bool extractValue(DataExtractor data, uint32_t *offset_ptr,
                     const DWARFUnit *u);
   bool isInlinedCStr() const {
diff --git a/lib/DebugInfo/DWARFFormValue.cpp b/lib/DebugInfo/DWARFFormValue.cpp
index 0a478613dae..69b97710a09 100644
--- a/lib/DebugInfo/DWARFFormValue.cpp
+++ b/lib/DebugInfo/DWARFFormValue.cpp
@@ -139,6 +139,8 @@ bool DWARFFormValue::extractValue(DataExtractor data, uint32_t *offset_ptr,
     switch (Form) {
     case DW_FORM_addr:
     case DW_FORM_ref_addr: {
+      if (!cu)
+        return false;
       uint16_t AddrSize =
           (Form == DW_FORM_addr)
               ? cu->getAddressByteSize()
@@ -179,8 +181,10 @@ bool DWARFFormValue::extractValue(DataExtractor data, uint32_t *offset_ptr,
       break;
     case DW_FORM_data4:
     case DW_FORM_ref4: {
-      RelocAddrMap::const_iterator AI = cu->getRelocMap()->find(*offset_ptr);
       Value.uval = data.getU32(offset_ptr);
+      if (!cu)
+        break;
+      RelocAddrMap::const_iterator AI = cu->getRelocMap()->find(*offset_ptr-4);
       if (AI != cu->getRelocMap()->end())
         Value.uval += AI->second.second;
       break;
@@ -193,13 +197,12 @@ bool DWARFFormValue::extractValue(DataExtractor data, uint32_t *offset_ptr,
       Value.sval = data.getSLEB128(offset_ptr);
       break;
     case DW_FORM_strp: {
-      RelocAddrMap::const_iterator AI
-        = cu->getRelocMap()->find(*offset_ptr);
-      if (AI != cu->getRelocMap()->end()) {
-        const std::pair<uint8_t, int64_t> &R = AI->second;
-        Value.uval = data.getU32(offset_ptr) + R.second;
-      } else
-        Value.uval = data.getU32(offset_ptr);
+      Value.uval = data.getU32(offset_ptr);
+      if (!cu)
+        break;
+      RelocAddrMap::const_iterator AI = cu->getRelocMap()->find(*offset_ptr-4);
+      if (AI != cu->getRelocMap()->end())
+        Value.uval += AI->second.second;
       break;
     }
     case DW_FORM_udata:
@@ -215,13 +218,12 @@ bool DWARFFormValue::extractValue(DataExtractor data, uint32_t *offset_ptr,
       break;
     case DW_FORM_sec_offset: {
       // FIXME: This is 64-bit for DWARF64.
-      RelocAddrMap::const_iterator AI
-        = cu->getRelocMap()->find(*offset_ptr);
-      if (AI != cu->getRelocMap()->end()) {
-        const std::pair<uint8_t, int64_t> &R = AI->second;
-        Value.uval = data.getU32(offset_ptr) + R.second;
-      } else
-        Value.uval = data.getU32(offset_ptr);
+      Value.uval = data.getU32(offset_ptr);
+      if (!cu)
+        break;
+      RelocAddrMap::const_iterator AI = cu->getRelocMap()->find(*offset_ptr-4);
+      if (AI != cu->getRelocMap()->end())
+        Value.uval +=  AI->second.second;
       break;
     }
     case DW_FORM_flag_present: