diff --git a/llvm/include/llvm/ExecutionEngine/Orc/COFF.h b/llvm/include/llvm/ExecutionEngine/Orc/COFF.h
index adc9e9e171165..42a6c85a577fa 100644
--- a/llvm/include/llvm/ExecutionEngine/Orc/COFF.h
+++ b/llvm/include/llvm/ExecutionEngine/Orc/COFF.h
@@ -13,6 +13,7 @@
 #ifndef LLVM_EXECUTIONENGINE_ORC_COFF_H
 #define LLVM_EXECUTIONENGINE_ORC_COFF_H
 
+#include "llvm/Support/Compiler.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/MemoryBuffer.h"
 
@@ -31,8 +32,8 @@ class COFFImportFileScanner {
 public:
   COFFImportFileScanner(std::set<std::string> &ImportedDynamicLibraries)
       : ImportedDynamicLibraries(ImportedDynamicLibraries) {}
-  Expected<bool> operator()(object::Archive &A, MemoryBufferRef MemberBuf,
-                            size_t Index) const;
+  LLVM_ABI Expected<bool>
+  operator()(object::Archive &A, MemoryBufferRef MemberBuf, size_t Index) const;
 
 private:
   std::set<std::string> &ImportedDynamicLibraries;
diff --git a/llvm/include/llvm/Frontend/Directive/Spelling.h b/llvm/include/llvm/Frontend/Directive/Spelling.h
index a101489603254..a13e26e88823d 100644
--- a/llvm/include/llvm/Frontend/Directive/Spelling.h
+++ b/llvm/include/llvm/Frontend/Directive/Spelling.h
@@ -10,6 +10,7 @@
 
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/iterator_range.h"
+#include "llvm/Support/Compiler.h"
 
 #include <limits>
 #include <tuple>
@@ -33,7 +34,8 @@ struct Spelling {
   VersionRange Versions;
 };
 
-StringRef FindName(llvm::iterator_range<const Spelling *>, unsigned Version);
+LLVM_ABI StringRef FindName(llvm::iterator_range<const Spelling *>,
+                            unsigned Version);
 
 } // namespace llvm::directive
 
diff --git a/llvm/include/llvm/Frontend/Driver/CodeGenOptions.h b/llvm/include/llvm/Frontend/Driver/CodeGenOptions.h
index f0168c0407884..17ba28b6de443 100644
--- a/llvm/include/llvm/Frontend/Driver/CodeGenOptions.h
+++ b/llvm/include/llvm/Frontend/Driver/CodeGenOptions.h
@@ -63,7 +63,7 @@ enum ProfileInstrKind {
 };
 
 // Default filename used for profile generation.
-std::string getDefaultProfileGenName();
+LLVM_ABI std::string getDefaultProfileGenName();
 } // end namespace llvm::driver
 
 #endif
diff --git a/llvm/include/llvm/Frontend/HLSL/HLSLRootSignatureUtils.h b/llvm/include/llvm/Frontend/HLSL/HLSLRootSignatureUtils.h
index 4769fd0559965..2f78173f9348d 100644
--- a/llvm/include/llvm/Frontend/HLSL/HLSLRootSignatureUtils.h
+++ b/llvm/include/llvm/Frontend/HLSL/HLSLRootSignatureUtils.h
@@ -97,13 +97,14 @@ class ResourceRange {
 
   // Returns a reference to the first RangeInfo that overlaps with
   // [Info.LowerBound;Info.UpperBound], or, std::nullopt if there is no overlap
-  std::optional<const RangeInfo *> getOverlapping(const RangeInfo &Info) const;
+  LLVM_ABI std::optional<const RangeInfo *>
+  getOverlapping(const RangeInfo &Info) const;
 
   // Return the mapped RangeInfo at X or nullptr if no mapping exists
-  const RangeInfo *lookup(uint32_t X) const;
+  LLVM_ABI const RangeInfo *lookup(uint32_t X) const;
 
   // Removes all entries of the ResourceRange
-  void clear();
+  LLVM_ABI void clear();
 
   // Insert the required (sub-)intervals such that the interval of [a;b] =
   // [Info.LowerBound, Info.UpperBound] is covered and points to a valid
@@ -131,7 +132,7 @@ class ResourceRange {
   // Returns a reference to the first RangeInfo that overlaps with
   // [Info.LowerBound;Info.UpperBound], or, std::nullopt if there is no overlap
   // (equivalent to getOverlapping)
-  std::optional<const RangeInfo *> insert(const RangeInfo &Info);
+  LLVM_ABI std::optional<const RangeInfo *> insert(const RangeInfo &Info);
 };
 
 } // namespace rootsig
diff --git a/llvm/include/llvm/TargetParser/TargetParser.h b/llvm/include/llvm/TargetParser/TargetParser.h
index 2ea7829d668a4..9b8d1f3c31121 100644
--- a/llvm/include/llvm/TargetParser/TargetParser.h
+++ b/llvm/include/llvm/TargetParser/TargetParser.h
@@ -214,7 +214,7 @@ struct BasicSubtargetSubTypeKV {
   }
 };
 
-std::optional<llvm::StringMap<bool>>
+LLVM_ABI std::optional<llvm::StringMap<bool>>
 getCPUDefaultTargetFeatures(StringRef CPU,
                             ArrayRef<BasicSubtargetSubTypeKV> ProcDesc,
                             ArrayRef<BasicSubtargetFeatureKV> ProcFeatures);