diff --git a/codon/compiler/debug_listener.cpp b/codon/compiler/debug_listener.cpp
index 0ae79e90..e54ed9c7 100644
--- a/codon/compiler/debug_listener.cpp
+++ b/codon/compiler/debug_listener.cpp
@@ -15,11 +15,7 @@ void DebugListener::notifyObjectLoaded(ObjectKey key,
       break;
     }
   }
-
-  auto buf = llvm::MemoryBuffer::getMemBufferCopy(obj.getData(), obj.getFileName());
-  auto newObj = llvm::cantFail(
-      llvm::object::ObjectFile::createObjectFile(buf->getMemBufferRef()));
-  objects.emplace_back(key, std::move(newObj), std::move(buf), start, stop);
+  objects.emplace_back(key, &obj, start, stop);
 }
 
 void DebugListener::notifyFreeingObject(ObjectKey key) {
@@ -29,10 +25,9 @@ void DebugListener::notifyFreeingObject(ObjectKey key) {
       objects.end());
 }
 
-llvm::Expected<llvm::DILineInfo> DebugListener::symbolize(intptr_t pc) const {
+llvm::Expected<llvm::DILineInfo> DebugListener::symbolize(intptr_t pc) {
   for (const auto &o : objects) {
     if (o.contains(pc)) {
-      llvm::symbolize::LLVMSymbolizer sym;
       return sym.symbolizeCode(o.getObject(),
                                {static_cast<uint64_t>(pc - o.getStart()),
                                 llvm::object::SectionedAddress::UndefSection});
diff --git a/codon/compiler/debug_listener.h b/codon/compiler/debug_listener.h
index 01d12e61..2e8c5d7b 100644
--- a/codon/compiler/debug_listener.h
+++ b/codon/compiler/debug_listener.h
@@ -12,27 +12,24 @@ public:
   class ObjectInfo {
   private:
     ObjectKey key;
-    std::unique_ptr<llvm::object::ObjectFile> object;
-    std::unique_ptr<llvm::MemoryBuffer> buffer;
+    const llvm::object::ObjectFile *object;
     intptr_t start;
     intptr_t stop;
 
   public:
-    ObjectInfo(ObjectKey key, std::unique_ptr<llvm::object::ObjectFile> object,
-               std::unique_ptr<llvm::MemoryBuffer> buffer, intptr_t start,
+    ObjectInfo(ObjectKey key, const llvm::object::ObjectFile *object, intptr_t start,
                intptr_t stop)
-        : key(key), object(std::move(object)), buffer(std::move(buffer)), start(start),
-          stop(stop) {}
+        : key(key), object(object), start(start), stop(stop) {}
 
     ObjectKey getKey() const { return key; }
     const llvm::object::ObjectFile &getObject() const { return *object; }
-    const llvm::MemoryBuffer &getBuffer() const { return *buffer; }
     intptr_t getStart() const { return start; }
     intptr_t getStop() const { return stop; }
     bool contains(intptr_t pc) const { return start <= pc && pc < stop; }
   };
 
 private:
+  llvm::symbolize::LLVMSymbolizer sym;
   std::vector<ObjectInfo> objects;
 
   void notifyObjectLoaded(ObjectKey key, const llvm::object::ObjectFile &obj,
@@ -40,9 +37,9 @@ private:
   void notifyFreeingObject(ObjectKey key) override;
 
 public:
-  DebugListener() : llvm::JITEventListener(), objects() {}
+  DebugListener() : llvm::JITEventListener(), sym(), objects() {}
 
-  llvm::Expected<llvm::DILineInfo> symbolize(intptr_t pc) const;
+  llvm::Expected<llvm::DILineInfo> symbolize(intptr_t pc);
 };
 
 } // namespace codon
diff --git a/codon/sir/llvm/llvisitor.cpp b/codon/sir/llvm/llvisitor.cpp
index e5ba4d84..b401f1cb 100644
--- a/codon/sir/llvm/llvisitor.cpp
+++ b/codon/sir/llvm/llvisitor.cpp
@@ -753,7 +753,7 @@ void LLVMVisitor::visit(const Module *x) {
   db.builder->finalize();
 }
 
-void LLVMVisitor::makeLLVMFunction(const Func *x) {
+llvm::DISubprogram *LLVMVisitor::getDISubprogramForFunc(const Func *x) {
   auto *srcInfo = getSrcInfo(x);
   llvm::DIFile *file = db.getFile(srcInfo->file);
   auto *derivedType = llvm::cast<llvm::DIDerivedType>(getDIType(x->getType()));
@@ -761,15 +761,17 @@ void LLVMVisitor::makeLLVMFunction(const Func *x) {
       llvm::cast<llvm::DISubroutineType>(derivedType->getRawBaseType());
   llvm::DISubprogram *subprogram = db.builder->createFunction(
       file, x->getUnmangledName(), getNameForFunction(x), file, srcInfo->line,
-      subroutineType, /*ScopeLine=*/0, llvm::DINode::FlagZero,
+      subroutineType, /*ScopeLine=*/0,
+      llvm::DINode::FlagAllCallsDescribed | llvm::DINode::FlagPrototyped,
       llvm::DISubprogram::toSPFlags(/*IsLocalToUnit=*/true,
                                     /*IsDefinition=*/true, /*IsOptimized=*/!db.debug));
+  return subprogram;
+}
 
+void LLVMVisitor::makeLLVMFunction(const Func *x) {
   // process LLVM functions in full immediately
   if (auto *llvmFunc = cast<LLVMFunc>(x)) {
     process(llvmFunc);
-    func = M->getFunction(getNameForFunction(x));
-    func->setSubprogram(subprogram);
     setDebugInfoForNode(nullptr);
     return;
   }
@@ -787,7 +789,7 @@ void LLVMVisitor::makeLLVMFunction(const Func *x) {
   func = llvm::cast<llvm::Function>(
       M->getOrInsertFunction(functionName, llvmFuncType).getCallee());
   if (!cast<ExternalFunc>(x)) {
-    func->setSubprogram(subprogram);
+    func->setSubprogram(getDISubprogramForFunc(x));
   }
 }
 
@@ -1020,6 +1022,19 @@ void LLVMVisitor::visit(const LLVMFunc *x) {
   seqassert(func, "function not linked in");
   func->setLinkage(getDefaultLinkage());
   func->addFnAttr(llvm::Attribute::AttrKind::AlwaysInline);
+  func->setSubprogram(getDISubprogramForFunc(x));
+
+  // set up debug info
+  // for now we just set all to func's source location
+  auto *srcInfo = getSrcInfo(x);
+  for (auto &block : func->getBasicBlockList()) {
+    for (auto &inst : block) {
+      if (!inst.getDebugLoc()) {
+        inst.setDebugLoc(llvm::DebugLoc(llvm::DILocation::get(
+            *context, srcInfo->line, srcInfo->col, func->getSubprogram())));
+      }
+    }
+  }
 }
 
 void LLVMVisitor::visit(const BodiedFunc *x) {
@@ -1047,7 +1062,6 @@ void LLVMVisitor::visit(const BodiedFunc *x) {
   auto *returnType = funcType->getReturnType();
   auto *entryBlock = llvm::BasicBlock::Create(*context, "entry", func);
   B->SetInsertPoint(entryBlock);
-  B->SetCurrentDebugLocation(llvm::DebugLoc());
 
   // set up arguments and other symbols
   seqassert(std::distance(func->arg_begin(), func->arg_end()) ==
diff --git a/codon/sir/llvm/llvisitor.h b/codon/sir/llvm/llvisitor.h
index 10b29797..0191daa2 100644
--- a/codon/sir/llvm/llvisitor.h
+++ b/codon/sir/llvm/llvisitor.h
@@ -192,6 +192,7 @@ private:
     funcs.emplace(func->getId(), x);
   }
   llvm::Value *getDummyVoidValue() { return llvm::ConstantTokenNone::get(*context); }
+  llvm::DISubprogram *getDISubprogramForFunc(const Func *x);
 
 public:
   static std::string getNameForFunction(const Func *x) {
diff --git a/codon/sir/llvm/optimize.cpp b/codon/sir/llvm/optimize.cpp
index 28217f48..39992196 100644
--- a/codon/sir/llvm/optimize.cpp
+++ b/codon/sir/llvm/optimize.cpp
@@ -54,10 +54,9 @@ void applyDebugTransformations(llvm::Module *module, bool debug) {
     // remove tail calls and fix linkage for stack traces
     for (auto &f : *module) {
       f.setLinkage(llvm::GlobalValue::ExternalLinkage);
-      if (f.hasFnAttribute(llvm::Attribute::AttrKind::AlwaysInline)) {
-        f.removeFnAttr(llvm::Attribute::AttrKind::AlwaysInline);
+      if (!f.hasFnAttribute(llvm::Attribute::AttrKind::AlwaysInline)) {
+        f.addFnAttr(llvm::Attribute::AttrKind::NoInline);
       }
-      f.addFnAttr(llvm::Attribute::AttrKind::NoInline);
       f.setHasUWTable();
       f.addFnAttr("no-frame-pointer-elim", "true");
       f.addFnAttr("no-frame-pointer-elim-non-leaf");