diff --git a/optimum/exporters/onnx/model_configs.py b/optimum/exporters/onnx/model_configs.py
index 5d7c29b4f45..ed270660bbd 100644
--- a/optimum/exporters/onnx/model_configs.py
+++ b/optimum/exporters/onnx/model_configs.py
@@ -76,6 +76,7 @@
     FalconModelPatcher,
     MistralModelPatcher,
     MusicgenModelPatcher,
+    Phi3ModelPatcher,
     SAMModelPatcher,
     SentenceTransformersCLIPPatcher,
     SentenceTransformersTransformerPatcher,
@@ -304,6 +305,11 @@ class Phi3OnnxConfig(PhiOnnxConfig):
     NORMALIZED_CONFIG_CLASS = NormalizedTextConfigWithGQA
     MIN_TRANSFORMERS_VERSION = version.parse("4.41.0")
 
+    def patch_model_for_export(
+        self, model: Union["PreTrainedModel", "TFPreTrainedModel"], model_kwargs: Optional[Dict[str, Any]] = None
+    ) -> "ModelPatcher":
+        return Phi3ModelPatcher(self, model, model_kwargs=model_kwargs)
+
 
 class MistralOnnxConfig(TextDecoderWithPositionIdsOnnxConfig):
     # This is because of the patching of torch.triu in AttentionMaskConverter, that exists from transformers>=4.35
@@ -2156,8 +2162,8 @@ class Pix2StructOnnxConfig(OnnxSeq2SeqConfigWithPast):
         DummySeq2SeqPastKeyValuesGenerator,
         DummyPix2StructInputGenerator,
     )
-    # Min operator needs to support int64, which is the case for opset>=12
-    DEFAULT_ONNX_OPSET = 12
+
+    DEFAULT_ONNX_OPSET = 14  # use 'aten::triu' now which is opset 14
 
     @property
     def inputs(self):
diff --git a/optimum/exporters/onnx/model_patcher.py b/optimum/exporters/onnx/model_patcher.py
index 34ed5fcae46..cad4a418808 100644
--- a/optimum/exporters/onnx/model_patcher.py
+++ b/optimum/exporters/onnx/model_patcher.py
@@ -1155,3 +1155,92 @@ def __exit__(self, exc_type, exc_value, traceback):
             from transformers.models.clip.modeling_clip import CLIPSdpaAttention
 
             CLIPSdpaAttention.forward = self.original_sdpa_forward
+
+
+# Copied from transformers.models.mistral.modeling_mistral.MistralModel._prepare_4d_causal_attention_mask_with_cache_position with Mistral->Phi3
+def _prepare_4d_causal_attention_mask_with_cache_position_patched(
+    attention_mask: torch.Tensor,
+    sequence_length: int,
+    target_length: int,
+    dtype: torch.dtype,
+    device: torch.device,
+    cache_position: torch.Tensor,
+    batch_size: int,
+    config: Any,
+    past_key_values: Any,
+):
+    """
+    Creates a causal 4D mask of shape `(batch_size, 1, query_length, key_value_length)` from a 2D mask of shape
+    `(batch_size, key_value_length)`, or if the input `attention_mask` is already 4D, do nothing.
+
+    Args:
+        attention_mask (`torch.Tensor`):
+            A 2D attention mask of shape `(batch_size, key_value_length)` or a 4D attention mask of shape `(batch_size, 1, query_length, key_value_length)`.
+        sequence_length (`int`):
+            The sequence length being processed.
+        target_length (`int`):
+            The target length: when generating with static cache, the mask should be as long as the static cache, to account for the 0 padding, the part of the cache that is not filled yet.
+        dtype (`torch.dtype`):
+            The dtype to use for the 4D attention mask.
+        device (`torch.device`):
+            The device to plcae the 4D attention mask on.
+        cache_position (`torch.Tensor`):
+            Indices depicting the position of the input sequence tokens in the sequence.
+        batch_size (`torch.Tensor`):
+            Batch size.
+        config (`Phi3Config`):
+            The model's configuration class
+        past_key_values (`Cache`):
+            The cache class that is being used currently to generate
+    """
+    if attention_mask is not None and attention_mask.dim() == 4:
+        # In this case we assume that the mask comes already in inverted form and requires no inversion or slicing.
+        causal_mask = attention_mask
+    else:
+        min_dtype = torch.finfo(dtype).min
+        causal_mask = torch.full((sequence_length, target_length), fill_value=min_dtype, dtype=dtype, device=device)
+        diagonal_attend_mask = torch.arange(target_length, device=device) > cache_position.reshape(-1, 1)
+        if config.sliding_window is not None:
+            # if we have sliding window, we should not attend to tokens beyond sliding window length, so we mask them out also
+            # the check is needed to verify is current checkpoint was trained with sliding window or not
+            if not isinstance(past_key_values, SlidingWindowCache) or sequence_length > target_length:
+                sliding_attend_mask = torch.arange(target_length, device=device) <= (
+                    cache_position.reshape(-1, 1) - config.sliding_window
+                )
+                diagonal_attend_mask.bitwise_or_(sliding_attend_mask)
+        causal_mask *= diagonal_attend_mask
+        causal_mask = causal_mask[None, None, :, :].expand(batch_size, 1, -1, -1)
+        if attention_mask is not None:
+            causal_mask = causal_mask.clone()  # copy to contiguous memory for in-place edit
+            if attention_mask.shape[-1] > target_length:
+                attention_mask = attention_mask[:, :target_length]
+            mask_length = attention_mask.shape[-1]
+            padding_mask = causal_mask[:, :, :, :mask_length] + attention_mask[:, None, None, :]
+            padding_mask = padding_mask == 0
+            causal_mask[:, :, :, :mask_length] = causal_mask[:, :, :, :mask_length].masked_fill(
+                padding_mask, min_dtype
+            )
+    return causal_mask
+
+
+from transformers import Phi3ForCausalLM
+
+
+class Phi3ModelPatcher(ModelPatcher):
+    def __init__(
+        self,
+        config: "OnnxConfig",
+        model: Phi3ForCausalLM,
+        model_kwargs: Optional[Dict[str, Any]] = None,
+    ):
+        super().__init__(config, model, model_kwargs)
+
+        if _transformers_version >= version.parse("4.46.0"):
+            if hasattr(self._model, "model"):
+                self._model.model._prepare_4d_causal_attention_mask_with_cache_position = (
+                    _prepare_4d_causal_attention_mask_with_cache_position_patched
+                )
+            else:
+                self._model._prepare_4d_causal_attention_mask_with_cache_position = (
+                    _prepare_4d_causal_attention_mask_with_cache_position_patched
+                )