diff --git a/.github/workflows/emscripten.yml b/.github/workflows/emscripten.yml
index 5c07655bd..98170ac6d 100644
--- a/.github/workflows/emscripten.yml
+++ b/.github/workflows/emscripten.yml
@@ -194,6 +194,9 @@ jobs:
                         -DLLVM_ENABLE_LIBPFM=OFF                        \
                         -DCLANG_BUILD_TOOLS=OFF                         \
                         -DLLVM_NATIVE_TOOL_DIR=$NATIVE_DIR 		\
+                        -DCMAKE_C_FLAGS_RELEASE="-Oz -g0" \
+                        -DCMAKE_CXX_FLAGS_RELEASE="-Oz -g0" \
+                        -DLLVM_ENABLE_LTO=Full \
                          ../llvm
           emmake ninja clang cling lld gtest_main
         else
@@ -225,6 +228,9 @@ jobs:
                         -DCLANG_BUILD_TOOLS=OFF                         \
                         -G Ninja                                         \
                         -DLLVM_NATIVE_TOOL_DIR=$NATIVE_DIR 		\
+                        -DCMAKE_C_FLAGS_RELEASE="-Oz -g0" \
+                        -DCMAKE_CXX_FLAGS_RELEASE="-Oz -g0" \
+                        -DLLVM_ENABLE_LTO=Full \
                         ../llvm
           emmake ninja libclang clangInterpreter clangStaticAnalyzerCore lldWasm
         fi
@@ -295,6 +301,9 @@ jobs:
                         -DLLVM_BUILD_TOOLS=OFF                          `
                         -DLLVM_ENABLE_LIBPFM=OFF                        `
                         -DCLANG_BUILD_TOOLS=OFF                         `
+                        -DCMAKE_C_FLAGS_RELEASE="-Oz -g0" `
+                        -DCMAKE_CXX_FLAGS_RELEASE="-Oz -g0" `
+                        -DLLVM_ENABLE_LTO=Full `
                 ..\llvm
           emmake make clang cling lld gtest_main
         }
@@ -335,6 +344,9 @@ jobs:
                         -DLLVM_BUILD_TOOLS=OFF                          `
                         -DLLVM_ENABLE_LIBPFM=OFF                        `
                         -DCLANG_BUILD_TOOLS=OFF                         `
+                        -DCMAKE_C_FLAGS_RELEASE="-Oz -g0" `
+                        -DCMAKE_CXX_FLAGS_RELEASE="-Oz -g0" `
+                        -DLLVM_ENABLE_LTO=Full `
                         -G Ninja `
                         ..\llvm
           emmake ninja libclang clangInterpreter clangStaticAnalyzerCore lldWasm
diff --git a/Emscripten-build-instructions.md b/Emscripten-build-instructions.md
index e41912bcc..74d1d0a7a 100644
--- a/Emscripten-build-instructions.md
+++ b/Emscripten-build-instructions.md
@@ -99,6 +99,9 @@ emcmake cmake -DCMAKE_BUILD_TYPE=Release \
                         -DLLVM_ENABLE_LIBPFM=OFF                        \
                         -DCLANG_BUILD_TOOLS=OFF                         \
                         -DLLVM_NATIVE_TOOL_DIR=$NATIVE_DIR              \
+                        -DCMAKE_C_FLAGS_RELEASE="-Oz -g0" \
+                        -DCMAKE_CXX_FLAGS_RELEASE="-Oz -g0" \
+                        -DLLVM_ENABLE_LTO=Full \
                         ../llvm
 emmake make libclang -j $(nproc --all)
 emmake make clangInterpreter clangStaticAnalyzerCore -j $(nproc --all)
@@ -130,6 +133,9 @@ emcmake cmake -DCMAKE_BUILD_TYPE=Release `
                         -DLLVM_ENABLE_LIBPFM=OFF                        `
                         -DCLANG_BUILD_TOOLS=OFF                         `
                         -G Ninja `
+                        -DCMAKE_C_FLAGS_RELEASE="-Oz -g0" `
+                        -DCMAKE_CXX_FLAGS_RELEASE="-Oz -g0" `
+                        -DLLVM_ENABLE_LTO=Full `
                         ..\llvm
 emmake ninja libclang clangInterpreter clangStaticAnalyzerCore lldWasm
 ```
diff --git a/docs/Emscripten-build-instructions.rst b/docs/Emscripten-build-instructions.rst
index 573627382..987b10f7f 100644
--- a/docs/Emscripten-build-instructions.rst
+++ b/docs/Emscripten-build-instructions.rst
@@ -119,6 +119,9 @@ and osx
                  -DLLVM_ENABLE_LIBPFM=OFF                        \
                  -DCLANG_BUILD_TOOLS=OFF                         \
                  -DLLVM_NATIVE_TOOL_DIR=$NATIVE_DIR 		\
+                 -DCMAKE_C_FLAGS_RELEASE="-Oz -g0" \
+                 -DCMAKE_CXX_FLAGS_RELEASE="-Oz -g0" \
+                 -DLLVM_ENABLE_LTO=Full \
                  ../llvm
    emmake make libclang -j $(nproc --all)
    emmake make clangInterpreter clangStaticAnalyzerCore -j $(nproc --all)
@@ -150,6 +153,9 @@ or executing
                         -DLLVM_ENABLE_LIBPFM=OFF                        `
                         -DCLANG_BUILD_TOOLS=OFF                         `
                         -G Ninja `
+                        -DCMAKE_C_FLAGS_RELEASE="-Oz -g0" `
+                        -DCMAKE_CXX_FLAGS_RELEASE="-Oz -g0" `
+                        -DLLVM_ENABLE_LTO=Full `
                         ..\llvm
    emmake ninja libclang clangInterpreter clangStaticAnalyzerCore lldWasm
 
diff --git a/lib/CppInterOp/CMakeLists.txt b/lib/CppInterOp/CMakeLists.txt
index 142d4d5d9..5a4fa9f96 100644
--- a/lib/CppInterOp/CMakeLists.txt
+++ b/lib/CppInterOp/CMakeLists.txt
@@ -127,10 +127,16 @@ if(EMSCRIPTEN)
   set_target_properties(clangCppInterOp
     PROPERTIES NO_SONAME 1
   )
+  target_compile_options(clangCppInterOp
+    PRIVATE "SHELL: -Oz"
+    PRIVATE "SHELL: -flto"
+  )
   target_link_options(clangCppInterOp
     PRIVATE "SHELL: -s WASM_BIGINT"
     PRIVATE "SHELL: -s SIDE_MODULE=1"
     PRIVATE "SHELL: ${SYMBOLS_LIST}"
+    PRIVATE "SHELL: -Oz"
+    PRIVATE "SHELL: -flto"
   )
 else()
   target_link_options(clangCppInterOp
diff --git a/lib/CppInterOp/exports.ld b/lib/CppInterOp/exports.ld
index 49b7b0d83..e22490f2a 100644
--- a/lib/CppInterOp/exports.ld
+++ b/lib/CppInterOp/exports.ld
@@ -50,4 +50,5 @@
 -Wl,--export=_ZNK5clang4Type14isFloatingTypeEv
 -Wl,--export=_ZNK5clang12FunctionDecl12getNumParamsEv
 -Wl,--export=__clang_Interpreter_SetValueNoAlloc
--Wl,--export=__clang_Interpreter_SetValueWithAlloc
\ No newline at end of file
+-Wl,--export=__clang_Interpreter_SetValueWithAlloc
+-Wl,--export=_ZN4llvm15SmallVectorBaseIjE8set_sizeEm
\ No newline at end of file