diff --git a/llvm/lib/BinaryFormat/Dwarf.cpp b/llvm/lib/BinaryFormat/Dwarf.cpp
--- a/llvm/lib/BinaryFormat/Dwarf.cpp
+++ b/llvm/lib/BinaryFormat/Dwarf.cpp
@@ -737,6 +737,7 @@
     return 2;
 
   case DW_FORM_strx3:
+  case DW_FORM_addrx3:
     return 3;
 
   case DW_FORM_data4:
diff --git a/llvm/lib/CodeGen/AsmPrinter/DIE.cpp b/llvm/lib/CodeGen/AsmPrinter/DIE.cpp
--- a/llvm/lib/CodeGen/AsmPrinter/DIE.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DIE.cpp
@@ -385,6 +385,7 @@
   case dwarf::DW_FORM_strx2:
   case dwarf::DW_FORM_addrx2:
   case dwarf::DW_FORM_strx3:
+  case dwarf::DW_FORM_addrx3:
   case dwarf::DW_FORM_strp:
   case dwarf::DW_FORM_ref4:
   case dwarf::DW_FORM_data4:
diff --git a/llvm/lib/DebugInfo/DWARF/DWARFFormValue.cpp b/llvm/lib/DebugInfo/DWARF/DWARFFormValue.cpp
--- a/llvm/lib/DebugInfo/DWARF/DWARFFormValue.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFFormValue.cpp
@@ -160,9 +160,11 @@
     case DW_FORM_ref_sup8:
     case DW_FORM_strx1:
     case DW_FORM_strx2:
+    case DW_FORM_strx3:
     case DW_FORM_strx4:
     case DW_FORM_addrx1:
     case DW_FORM_addrx2:
+    case DW_FORM_addrx3:
     case DW_FORM_addrx4:
     case DW_FORM_sec_offset:
     case DW_FORM_strp:
@@ -300,6 +302,7 @@
       Value.uval = Data.getU16(OffsetPtr, &Err);
       break;
     case DW_FORM_strx3:
+    case DW_FORM_addrx3:
       Value.uval = Data.getU24(OffsetPtr, &Err);
       break;
     case DW_FORM_data4:
diff --git a/llvm/unittests/DebugInfo/DWARF/DWARFDebugInfoTest.cpp b/llvm/unittests/DebugInfo/DWARF/DWARFDebugInfoTest.cpp
--- a/llvm/unittests/DebugInfo/DWARF/DWARFDebugInfoTest.cpp
+++ b/llvm/unittests/DebugInfo/DWARF/DWARFDebugInfoTest.cpp
@@ -51,6 +51,7 @@
   const AddrType AddrxValue = (AddrType)0x4231abcd4231abcdULL;
   const AddrType Addrx1Value = (AddrType)0x0000aaaabbbbccccULL;
   const AddrType Addrx2Value = (AddrType)0xf00123f00456f000ULL;
+  const AddrType Addrx3Value = (AddrType)0xABABA000B111C222ULL;
   const AddrType Addrx4Value = (AddrType)0xa1b2c3d4e5f6e5d4ULL;
 
   const uint8_t BlockData[] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 0};
@@ -100,14 +101,14 @@
   const auto Attr_DW_FORM_addrx = static_cast<dwarf::Attribute>(Attr++);
   const auto Attr_DW_FORM_addrx1 = static_cast<dwarf::Attribute>(Attr++);
   const auto Attr_DW_FORM_addrx2 = static_cast<dwarf::Attribute>(Attr++);
-  // TODO: Add Attr_DW_FORM_addrx3 test (this form type is currently
-  // unsupported)
+  const auto Attr_DW_FORM_addrx3 = static_cast<dwarf::Attribute>(Attr++);
   const auto Attr_DW_FORM_addrx4 = static_cast<dwarf::Attribute>(Attr++);
 
   if (Version >= 5) {
     CUDie.addAttribute(Attr_DW_FORM_addrx, DW_FORM_addrx, AddrxValue);
     CUDie.addAttribute(Attr_DW_FORM_addrx1, DW_FORM_addrx1, Addrx1Value);
     CUDie.addAttribute(Attr_DW_FORM_addrx2, DW_FORM_addrx2, Addrx2Value);
+    CUDie.addAttribute(Attr_DW_FORM_addrx3, DW_FORM_addrx3, Addrx3Value);
     CUDie.addAttribute(Attr_DW_FORM_addrx4, DW_FORM_addrx4, Addrx4Value);
   }
 
@@ -275,6 +276,10 @@
     EXPECT_TRUE(ExtractedAddrx2Value.has_value());
     EXPECT_EQ(Addrx2Value, *ExtractedAddrx2Value);
 
+    auto ExtractedAddrx3Value = toAddress(DieDG.find(Attr_DW_FORM_addrx3));
+    EXPECT_TRUE(ExtractedAddrx3Value.has_value());
+    EXPECT_EQ(Addrx3Value, *ExtractedAddrx3Value);
+
     auto ExtractedAddrx4Value = toAddress(DieDG.find(Attr_DW_FORM_addrx4));
     EXPECT_TRUE(ExtractedAddrx1Value.has_value());
     EXPECT_EQ(Addrx4Value, *ExtractedAddrx4Value);
diff --git a/llvm/unittests/DebugInfo/DWARF/DWARFFormValueTest.cpp b/llvm/unittests/DebugInfo/DWARF/DWARFFormValueTest.cpp
--- a/llvm/unittests/DebugInfo/DWARF/DWARFFormValueTest.cpp
+++ b/llvm/unittests/DebugInfo/DWARF/DWARFFormValueTest.cpp
@@ -232,9 +232,11 @@
         ParamType(DW_FORM_ref_sup8, 0, 0, DWARF32, SampleU32, 8, true),
         ParamType(DW_FORM_strx1, 0, 0, DWARF32, SampleU32, 1, true),
         ParamType(DW_FORM_strx2, 0, 0, DWARF32, SampleU32, 2, true),
+        ParamType(DW_FORM_strx3, 0, 0, DWARF32, SampleU32, 3, true),
         ParamType(DW_FORM_strx4, 0, 0, DWARF32, SampleU32, 4, true),
         ParamType(DW_FORM_addrx1, 0, 0, DWARF32, SampleU32, 1, true),
         ParamType(DW_FORM_addrx2, 0, 0, DWARF32, SampleU32, 2, true),
+        ParamType(DW_FORM_addrx3, 0, 0, DWARF32, SampleU32, 3, true),
         ParamType(DW_FORM_addrx4, 0, 0, DWARF32, SampleU32, 4, true),
         ParamType(DW_FORM_sec_offset, 0, 1, DWARF32, SampleU32, 0, false),
         ParamType(DW_FORM_sec_offset, 1, 0, DWARF32, SampleU32, 0, false),