diff --git a/llm/generate/gen_linux.sh b/llm/generate/gen_linux.sh
index 279ed874..b402ecad 100755
--- a/llm/generate/gen_linux.sh
+++ b/llm/generate/gen_linux.sh
@@ -172,7 +172,15 @@ if [ -d "${CUDA_LIB_DIR}" ]; then
         # Disabling has minimal performance effect while maintaining compatibility. 
         ARM64_DEFS="-DLLAMA_AVX=off -DLLAMA_AVX2=off -DLLAMA_AVX512=off -DLLAMA_CUDA_F16=off"
     fi
-    CMAKE_DEFS="-DLLAMA_CUDA=on -DLLAMA_CUDA_FORCE_MMQ=on -DCMAKE_CUDA_ARCHITECTURES=${CMAKE_CUDA_ARCHITECTURES} ${COMMON_CMAKE_DEFS} ${CMAKE_DEFS} ${ARM64_DEFS}"
+    # Users building from source can tune the exact flags we pass to cmake for configuring llama.cpp
+    if [ -n "${OLLAMA_CUSTOM_CUDA_DEFS}" ]; then
+        echo "OLLAMA_CUSTOM_CUDA_DEFS=\"${OLLAMA_CUSTOM_CUDA_DEFS}\""
+        CMAKE_CUDA_DEFS="-DLLAMA_CUDA=on -DCMAKE_CUDA_ARCHITECTURES=${CMAKE_CUDA_ARCHITECTURES} ${OLLAMA_CUSTOM_CUDA_DEFS}"
+        echo "Building custom CUDA GPU"
+    else
+        CMAKE_CUDA_DEFS="-DLLAMA_CUDA=on -DLLAMA_CUDA_FORCE_MMQ=on -DCMAKE_CUDA_ARCHITECTURES=${CMAKE_CUDA_ARCHITECTURES}"
+    fi
+    CMAKE_DEFS="${COMMON_CMAKE_DEFS} ${CMAKE_DEFS} ${ARM64_DEFS} ${CMAKE_CUDA_DEFS}"
     BUILD_DIR="../build/linux/${ARCH}/cuda${CUDA_VARIANT}"
     EXTRA_LIBS="-L${CUDA_LIB_DIR} -lcudart -lcublas -lcublasLt -lcuda"
     build
@@ -217,6 +225,12 @@ if [ -d "${ROCM_PATH}" ]; then
     fi
     init_vars
     CMAKE_DEFS="${COMMON_CMAKE_DEFS} ${CMAKE_DEFS} -DLLAMA_HIPBLAS=on -DCMAKE_C_COMPILER=$ROCM_PATH/llvm/bin/clang -DCMAKE_CXX_COMPILER=$ROCM_PATH/llvm/bin/clang++ -DAMDGPU_TARGETS=$(amdGPUs) -DGPU_TARGETS=$(amdGPUs)"
+    # Users building from source can tune the exact flags we pass to cmake for configuring llama.cpp
+    if [ -n "${OLLAMA_CUSTOM_ROCM_DEFS}" ]; then
+        echo "OLLAMA_CUSTOM_ROCM_DEFS=\"${OLLAMA_CUSTOM_ROCM_DEFS}\""
+        CMAKE_DEFS="${CMAKE_DEFS} ${OLLAMA_CUSTOM_ROCM_DEFS}"
+        echo "Building custom ROCM GPU"
+    fi
     BUILD_DIR="../build/linux/${ARCH}/rocm${ROCM_VARIANT}"
     EXTRA_LIBS="-L${ROCM_PATH}/lib -L/opt/amdgpu/lib/x86_64-linux-gnu/ -Wl,-rpath,\$ORIGIN/../../rocm/ -lhipblas -lrocblas -lamdhip64 -lrocsolver -lamd_comgr -lhsa-runtime64 -lrocsparse -ldrm -ldrm_amdgpu"
     build
diff --git a/llm/generate/gen_windows.ps1 b/llm/generate/gen_windows.ps1
index 0d2ae57f..5071e09f 100644
--- a/llm/generate/gen_windows.ps1
+++ b/llm/generate/gen_windows.ps1
@@ -243,6 +243,11 @@ if ($null -ne $script:CUDA_LIB_DIR) {
     init_vars
     $script:buildDir="../build/windows/${script:ARCH}/cuda$script:CUDA_VARIANT"
     $script:cmakeDefs += @("-A", "x64", "-DLLAMA_CUDA=ON", "-DLLAMA_AVX=on", "-DLLAMA_AVX2=off", "-DCUDAToolkit_INCLUDE_DIR=$script:CUDA_INCLUDE_DIR", "-DCMAKE_CUDA_ARCHITECTURES=${script:CMAKE_CUDA_ARCHITECTURES}")
+    if ($null -ne $env:OLLAMA_CUSTOM_CUDA_DEFS) {
+        write-host "OLLAMA_CUSTOM_CUDA_DEFS=`"${env:OLLAMA_CUSTOM_CUDA_DEFS}`""
+        $script:cmakeDefs +=@("${env:OLLAMA_CUSTOM_CUDA_DEFS}")
+        write-host "building custom CUDA GPU"
+    }
     build
     sign
     compress
@@ -274,7 +279,11 @@ if ($null -ne $env:HIP_PATH) {
 
     # We have to clobber the LIB var from the developer shell for clang to work properly
     $env:LIB=""
-
+    if ($null -ne $env:OLLAMA_CUSTOM_ROCM_DEFS) {
+        write-host "OLLAMA_CUSTOM_ROCM_DEFS=`"${env:OLLAMA_CUSTOM_ROCM_DEFS}`""
+        $script:cmakeDefs += @("${env:OLLAMA_CUSTOM_ROCM_DEFS}")
+        write-host "building custom ROCM GPU"
+    }
     write-host "Building ROCm"
     build
     # Ninja doesn't prefix with config name