Index: include/llvm/DebugInfo/DWARFFormValue.h
===================================================================
--- include/llvm/DebugInfo/DWARFFormValue.h
+++ include/llvm/DebugInfo/DWARFFormValue.h
@@ -67,6 +67,7 @@
   /// DWARFFormValue has form class is suitable for representing Foo.
   Optional<uint64_t> getAsReference(const DWARFUnit *U) const;
   Optional<uint64_t> getAsUnsignedConstant() const;
+  Optional<int64_t> getAsSignedConstant() const;
   Optional<const char *> getAsCString(const DWARFUnit *U) const;
   Optional<uint64_t> getAsAddress(const DWARFUnit *U) const;
   Optional<uint64_t> getAsSectionOffset() const;
Index: lib/DebugInfo/DWARFFormValue.cpp
===================================================================
--- lib/DebugInfo/DWARFFormValue.cpp
+++ lib/DebugInfo/DWARFFormValue.cpp
@@ -549,6 +549,24 @@
   return Value.uval;
 }
 
+Optional<int64_t> DWARFFormValue::getAsSignedConstant() const {
+  if ((!isFormClass(FC_Constant) && !isFormClass(FC_Flag))
+      || Form == DW_FORM_udata)
+    return None;
+  switch (Form) {
+  case DW_FORM_data4:
+    return (int32_t)Value.uval;
+  case DW_FORM_data2:
+    return (int16_t)Value.uval;
+  case DW_FORM_data1:
+    return (int8_t)Value.uval;
+  case DW_FORM_sdata:
+  case DW_FORM_data8:
+  default:
+    return Value.sval;
+  }
+}
+
 Optional<ArrayRef<uint8_t>> DWARFFormValue::getAsBlock() const {
   if (!isFormClass(FC_Block) && !isFormClass(FC_Exprloc))
     return None;
Index: unittests/DebugInfo/DWARFFormValueTest.cpp
===================================================================
--- unittests/DebugInfo/DWARFFormValueTest.cpp
+++ unittests/DebugInfo/DWARFFormValueTest.cpp
@@ -7,6 +7,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "../lib/DebugInfo/DWARFContext.h"
 #include "llvm/DebugInfo/DWARFFormValue.h"
 #include "llvm/Support/Dwarf.h"
 #include "gtest/gtest.h"
@@ -46,4 +47,67 @@
   EXPECT_TRUE(isFormClass(DW_FORM_ref_sig8, DWARFFormValue::FC_Reference));
 }
 
+
+class DWARFTestContext : public DWARFContext {
+  Section DummySection;
+  TypeSectionMap DummySectionMap;
+public:
+  bool isLittleEndian() const override { return sys::IsLittleEndianHost; }
+  uint8_t getAddressSize() const override { return sizeof(void *); }
+  const Section &getInfoSection() override { return DummySection; }
+  const TypeSectionMap &getTypesSections() override { return DummySectionMap; }
+  StringRef getAbbrevSection() override { return StringRef(); }
+  const Section &getLocSection() override { return DummySection; }
+  const Section &getLocDWOSection() override { return DummySection; }
+  StringRef getARangeSection() override { return StringRef(); }
+  StringRef getDebugFrameSection() override { return StringRef(); }
+  const Section &getLineSection() override { return DummySection; }
+  const Section &getLineDWOSection() override { return DummySection; }
+  StringRef getStringSection() override { return StringRef(); }
+  StringRef getRangeSection() override { return StringRef(); }
+  StringRef getPubNamesSection() override { return StringRef(); }
+  StringRef getPubTypesSection() override { return StringRef(); }
+  StringRef getGnuPubNamesSection() override { return StringRef(); }
+  StringRef getGnuPubTypesSection() override { return StringRef(); }
+  const Section &getInfoDWOSection() override { return DummySection; }
+  const TypeSectionMap &getTypesDWOSections() override { return DummySectionMap; }
+  StringRef getAbbrevDWOSection() override { return StringRef(); }
+  StringRef getStringDWOSection() override { return StringRef(); }
+  StringRef getStringOffsetDWOSection() override { return StringRef(); }
+  StringRef getRangeDWOSection() override { return StringRef(); }
+  StringRef getAddrSection() override { return StringRef(); }
+};
+
+
+static DWARFTestContext TestContext;
+static DWARFUnitSection<DWARFCompileUnit> DummyUnitSection;
+static RelocAddrMap DummyRelocMap;
+static DWARFCompileUnit DummyCompileUnit(TestContext, nullptr, StringRef(),
+                                         StringRef(), StringRef(), StringRef(),
+                                         StringRef(), &DummyRelocMap,
+                                         sys::IsLittleEndianHost, DummyUnitSection);
+
+DWARFFormValue createFromValue(uint16_t Form, uint64_t Value) {
+  union {
+    uint64_t Val;
+    char     Raw[8];
+  } U = { Value };
+  uint32_t Offset = 0;
+  DWARFFormValue Result(Form);
+  DataExtractor Data(U.Raw, sys::IsLittleEndianHost, sizeof(void*));
+  Result.extractValue(Data, &Offset, &DummyCompileUnit);
+  return Result;
+}
+
+TEST(DWARFFormValue, SignedConstantForms) {
+  DWARFFormValue data1 = createFromValue(DW_FORM_data1, 0xFF);
+  DWARFFormValue data2 = createFromValue(DW_FORM_data2, 0xFFFF);
+  DWARFFormValue data4 = createFromValue(DW_FORM_data4, 0xFFFFFFFF);
+  DWARFFormValue data8 = createFromValue(DW_FORM_data8, 0xFFFFFFFFFFFFFFFF);
+  EXPECT_EQ(data1.getAsSignedConstant().getValue(), -1);
+  EXPECT_EQ(data2.getAsSignedConstant().getValue(), -1);
+  EXPECT_EQ(data4.getAsSignedConstant().getValue(), -1);
+  EXPECT_EQ(data8.getAsSignedConstant().getValue(), -1);
+}
+
 } // end anonymous namespace