diff --git a/flang/lib/Optimizer/Transforms/ExternalNameConversion.cpp b/flang/lib/Optimizer/Transforms/ExternalNameConversion.cpp
index 3a9686418c2ea..b265c74c33dd5 100644
--- a/flang/lib/Optimizer/Transforms/ExternalNameConversion.cpp
+++ b/flang/lib/Optimizer/Transforms/ExternalNameConversion.cpp
@@ -12,13 +12,9 @@
 #include "flang/Optimizer/Dialect/FIROpsSupport.h"
 #include "flang/Optimizer/Support/InternalNames.h"
 #include "flang/Optimizer/Transforms/Passes.h"
-#include "mlir/Dialect/LLVMIR/LLVMDialect.h"
-#include "mlir/Dialect/OpenACC/OpenACC.h"
-#include "mlir/Dialect/OpenMP/OpenMPDialect.h"
 #include "mlir/IR/Attributes.h"
 #include "mlir/IR/SymbolTable.h"
 #include "mlir/Pass/Pass.h"
-#include "mlir/Transforms/DialectConversion.h"
 
 namespace fir {
 #define GEN_PASS_DEF_EXTERNALNAMECONVERSION
@@ -44,102 +40,8 @@ mangleExternalName(const std::pair<fir::NameUniquer::NameKind,
                                                   appendUnderscore);
 }
 
-//===----------------------------------------------------------------------===//
-// Rewrite patterns
-//===----------------------------------------------------------------------===//
-
 namespace {
 
-struct MangleNameOnFuncOp : public mlir::OpRewritePattern<mlir::func::FuncOp> {
-public:
-  using OpRewritePattern::OpRewritePattern;
-
-  MangleNameOnFuncOp(mlir::MLIRContext *ctx, bool appendUnderscore)
-      : mlir::OpRewritePattern<mlir::func::FuncOp>(ctx),
-        appendUnderscore(appendUnderscore) {}
-
-  mlir::LogicalResult
-  matchAndRewrite(mlir::func::FuncOp op,
-                  mlir::PatternRewriter &rewriter) const override {
-    mlir::LogicalResult ret = success();
-    rewriter.startOpModification(op);
-    llvm::StringRef oldName = op.getSymName();
-    auto result = fir::NameUniquer::deconstruct(oldName);
-    if (fir::NameUniquer::isExternalFacingUniquedName(result)) {
-      auto newSymbol =
-          rewriter.getStringAttr(mangleExternalName(result, appendUnderscore));
-
-      // Try to update all SymbolRef's in the module that match the current op
-      if (mlir::ModuleOp mod = op->getParentOfType<mlir::ModuleOp>())
-        ret = op.replaceAllSymbolUses(newSymbol, mod);
-
-      op.setSymNameAttr(newSymbol);
-      mlir::SymbolTable::setSymbolName(op, newSymbol);
-
-      op->setAttr(fir::getInternalFuncNameAttrName(),
-                  mlir::StringAttr::get(op->getContext(), oldName));
-    }
-    rewriter.finalizeOpModification(op);
-    return ret;
-  }
-
-private:
-  bool appendUnderscore;
-};
-
-struct MangleNameForCommonBlock : public mlir::OpRewritePattern<fir::GlobalOp> {
-public:
-  using OpRewritePattern::OpRewritePattern;
-
-  MangleNameForCommonBlock(mlir::MLIRContext *ctx, bool appendUnderscore)
-      : mlir::OpRewritePattern<fir::GlobalOp>(ctx),
-        appendUnderscore(appendUnderscore) {}
-
-  mlir::LogicalResult
-  matchAndRewrite(fir::GlobalOp op,
-                  mlir::PatternRewriter &rewriter) const override {
-    rewriter.startOpModification(op);
-    auto result = fir::NameUniquer::deconstruct(
-        op.getSymref().getRootReference().getValue());
-    if (fir::NameUniquer::isExternalFacingUniquedName(result)) {
-      auto newName = mangleExternalName(result, appendUnderscore);
-      op.setSymrefAttr(mlir::SymbolRefAttr::get(op.getContext(), newName));
-      SymbolTable::setSymbolName(op, newName);
-    }
-    rewriter.finalizeOpModification(op);
-    return success();
-  }
-
-private:
-  bool appendUnderscore;
-};
-
-struct MangleNameOnAddrOfOp : public mlir::OpRewritePattern<fir::AddrOfOp> {
-public:
-  using OpRewritePattern::OpRewritePattern;
-
-  MangleNameOnAddrOfOp(mlir::MLIRContext *ctx, bool appendUnderscore)
-      : mlir::OpRewritePattern<fir::AddrOfOp>(ctx),
-        appendUnderscore(appendUnderscore) {}
-
-  mlir::LogicalResult
-  matchAndRewrite(fir::AddrOfOp op,
-                  mlir::PatternRewriter &rewriter) const override {
-    auto result = fir::NameUniquer::deconstruct(
-        op.getSymbol().getRootReference().getValue());
-    if (fir::NameUniquer::isExternalFacingUniquedName(result)) {
-      auto newName = SymbolRefAttr::get(
-          op.getContext(), mangleExternalName(result, appendUnderscore));
-      rewriter.replaceOpWithNewOp<fir::AddrOfOp>(op, op.getResTy().getType(),
-                                                 newName);
-    }
-    return success();
-  }
-
-private:
-  bool appendUnderscore;
-};
-
 class ExternalNameConversionPass
     : public fir::impl::ExternalNameConversionBase<ExternalNameConversionPass> {
 public:
@@ -162,31 +64,42 @@ void ExternalNameConversionPass::runOnOperation() {
   auto *context = &getContext();
 
   appendUnderscores = (usePassOpt) ? appendUnderscoreOpt : appendUnderscores;
+  llvm::DenseMap<mlir::StringAttr, mlir::FlatSymbolRefAttr> remappings;
+  // Update names of external Fortran functions and names of Common Block
+  // globals.
+  for (auto &funcOrGlobal : op->getRegion(0).front()) {
+    if (llvm::isa<mlir::func::FuncOp>(funcOrGlobal) ||
+        llvm::isa<fir::GlobalOp>(funcOrGlobal)) {
+      auto symName = funcOrGlobal.getAttrOfType<mlir::StringAttr>(
+          mlir::SymbolTable::getSymbolAttrName());
+      auto deconstructedName = fir::NameUniquer::deconstruct(symName);
+      if (fir::NameUniquer::isExternalFacingUniquedName(deconstructedName)) {
+        auto newName = mangleExternalName(deconstructedName, appendUnderscores);
+        auto newAttr = mlir::StringAttr::get(context, newName);
+        mlir::SymbolTable::setSymbolName(&funcOrGlobal, newAttr);
+        auto newSymRef = mlir::FlatSymbolRefAttr::get(newAttr);
+        remappings.try_emplace(symName, newSymRef);
+        if (llvm::isa<mlir::func::FuncOp>(funcOrGlobal))
+          funcOrGlobal.setAttr(fir::getInternalFuncNameAttrName(), symName);
+      }
+    }
+  }
 
-  mlir::RewritePatternSet patterns(context);
-  patterns.insert<MangleNameOnFuncOp, MangleNameForCommonBlock,
-                  MangleNameOnAddrOfOp>(context, appendUnderscores);
-
-  ConversionTarget target(*context);
-  target.addLegalDialect<fir::FIROpsDialect, LLVM::LLVMDialect,
-                         acc::OpenACCDialect, omp::OpenMPDialect>();
-
-  target.addDynamicallyLegalOp<mlir::func::FuncOp>([](mlir::func::FuncOp op) {
-    return !fir::NameUniquer::needExternalNameMangling(op.getSymName());
-  });
-
-  target.addDynamicallyLegalOp<fir::GlobalOp>([](fir::GlobalOp op) {
-    return !fir::NameUniquer::needExternalNameMangling(
-        op.getSymref().getRootReference().getValue());
-  });
-
-  target.addDynamicallyLegalOp<fir::AddrOfOp>([](fir::AddrOfOp op) {
-    return !fir::NameUniquer::needExternalNameMangling(
-        op.getSymbol().getRootReference().getValue());
+  if (remappings.empty())
+    return;
+
+  // Update all uses of the functions and globals that have been renamed.
+  op.walk([&remappings](mlir::Operation *nestedOp) {
+    llvm::SmallVector<std::pair<mlir::StringAttr, mlir::SymbolRefAttr>> updates;
+    for (const mlir::NamedAttribute &attr : nestedOp->getAttrDictionary())
+      if (auto symRef = llvm::dyn_cast<mlir::SymbolRefAttr>(attr.getValue()))
+        if (auto remap = remappings.find(symRef.getRootReference());
+            remap != remappings.end())
+          updates.emplace_back(std::pair<mlir::StringAttr, mlir::SymbolRefAttr>{
+              attr.getName(), mlir::SymbolRefAttr(remap->second)});
+    for (auto update : updates)
+      nestedOp->setAttr(update.first, update.second);
   });
-
-  if (failed(applyPartialConversion(op, target, std::move(patterns))))
-    signalPassFailure();
 }
 
 std::unique_ptr<mlir::Pass> fir::createExternalNameConversionPass() {