Index: flang/include/flang/Optimizer/Support/InternalNames.h
===================================================================
--- flang/include/flang/Optimizer/Support/InternalNames.h
+++ flang/include/flang/Optimizer/Support/InternalNames.h
@@ -32,6 +32,7 @@
   /// The sort of the unique name
   enum class NameKind {
     NOT_UNIQUED,
+    BLOCK_DATA_NAME,
     COMMON,
     CONSTANT,
     DERIVED_TYPE,
@@ -63,6 +64,9 @@
   /// Unique a common block name
   std::string doCommonBlock(llvm::StringRef name);
 
+  /// Unique a block data unit name
+  std::string doBlockData(llvm::StringRef name);
+
   /// Unique a (global) constant name
   std::string doConstant(llvm::ArrayRef<llvm::StringRef> modules,
                          llvm::Optional<llvm::StringRef> host,
Index: flang/lib/Optimizer/Support/InternalNames.cpp
===================================================================
--- flang/lib/Optimizer/Support/InternalNames.cpp
+++ flang/lib/Optimizer/Support/InternalNames.cpp
@@ -7,7 +7,9 @@
 //===----------------------------------------------------------------------===//
 
 #include "flang/Optimizer/Support/InternalNames.h"
+#include "flang/Optimizer/Dialect/FIRType.h"
 #include "mlir/IR/Diagnostics.h"
+#include "mlir/IR/BuiltinTypes.h"
 #include "llvm/Support/CommandLine.h"
 
 static llvm::cl::opt<std::string> mainEntryName(
@@ -97,6 +99,11 @@
   return result.append("B").append(toLower(name));
 }
 
+std::string fir::NameUniquer::doBlockData(llvm::StringRef name) {
+  std::string result = prefix();
+  return result.append("L").append(toLower(name));
+}
+
 std::string
 fir::NameUniquer::doConstant(llvm::ArrayRef<llvm::StringRef> modules,
                              llvm::Optional<llvm::StringRef> host,
@@ -237,6 +244,10 @@
           name = readName(uniq, i, i + 1, end);
         }
         break;
+      case 'L':
+        nk = NameKind::BLOCK_DATA_NAME;
+        name = readName(uniq, i, i + 1, end);
+        break;
       case 'P':
         nk = NameKind::PROCEDURE;
         name = readName(uniq, i, i + 1, end);
Index: flang/unittests/Optimizer/InternalNamesTest.cpp
===================================================================
--- flang/unittests/Optimizer/InternalNamesTest.cpp
+++ flang/unittests/Optimizer/InternalNamesTest.cpp
@@ -46,6 +46,16 @@
       << "Possible error: DeconstructedName mismatch";
 }
 
+TEST(InternalNamesTest, doBlockDataTest) {
+  NameUniquer obj;
+  std::string actual = obj.doBlockData("blockdatatest");
+  std::string actualBlank = obj.doBlockData("");
+  std::string expectedMangledName = "_QLblockdatatest";
+  std::string expectedMangledNameBlank = "_QL";
+  ASSERT_EQ(actual, expectedMangledName);
+  ASSERT_EQ(actualBlank, expectedMangledNameBlank);
+}
+
 TEST(InternalNamesTest, doCommonBlockTest) {
   NameUniquer obj;
   std::string actual = obj.doCommonBlock("hello");