diff --git a/egs/ljspeech/TTS/matcha/monotonic_align/.gitignore b/egs/ljspeech/TTS/matcha/monotonic_align/.gitignore
new file mode 100644
index 000000000..3def4ae26
--- /dev/null
+++ b/egs/ljspeech/TTS/matcha/monotonic_align/.gitignore
@@ -0,0 +1,3 @@
+build
+core.c
+*.so
\ No newline at end of file
diff --git a/egs/ljspeech/TTS/matcha/monotonic_align/__init__.py b/egs/ljspeech/TTS/matcha/monotonic_align/__init__.py
new file mode 100644
index 000000000..eee6e0d47
--- /dev/null
+++ b/egs/ljspeech/TTS/matcha/monotonic_align/__init__.py
@@ -0,0 +1,22 @@
+import numpy as np
+import torch
+
+from matcha.utils.monotonic_align.core import maximum_path_c
+
+
+def maximum_path(value, mask):
+    """Cython optimised version.
+    value: [b, t_x, t_y]
+    mask: [b, t_x, t_y]
+    """
+    value = value * mask
+    device = value.device
+    dtype = value.dtype
+    value = value.data.cpu().numpy().astype(np.float32)
+    path = np.zeros_like(value).astype(np.int32)
+    mask = mask.data.cpu().numpy()
+
+    t_x_max = mask.sum(1)[:, 0].astype(np.int32)
+    t_y_max = mask.sum(2)[:, 0].astype(np.int32)
+    maximum_path_c(path, value, t_x_max, t_y_max)
+    return torch.from_numpy(path).to(device=device, dtype=dtype)
diff --git a/egs/ljspeech/TTS/matcha/monotonic_align/core.pyx b/egs/ljspeech/TTS/matcha/monotonic_align/core.pyx
new file mode 100644
index 000000000..091fcc3a5
--- /dev/null
+++ b/egs/ljspeech/TTS/matcha/monotonic_align/core.pyx
@@ -0,0 +1,47 @@
+import numpy as np
+
+cimport cython
+cimport numpy as np
+
+from cython.parallel import prange
+
+
+@cython.boundscheck(False)
+@cython.wraparound(False)
+cdef void maximum_path_each(int[:,::1] path, float[:,::1] value, int t_x, int t_y, float max_neg_val) nogil:
+  cdef int x
+  cdef int y
+  cdef float v_prev
+  cdef float v_cur
+  cdef float tmp
+  cdef int index = t_x - 1
+
+  for y in range(t_y):
+    for x in range(max(0, t_x + y - t_y), min(t_x, y + 1)):
+      if x == y:
+        v_cur = max_neg_val
+      else:
+        v_cur = value[x, y-1]
+      if x == 0:
+        if y == 0:
+          v_prev = 0.
+        else:
+          v_prev = max_neg_val
+      else:
+        v_prev = value[x-1, y-1]
+      value[x, y] = max(v_cur, v_prev) + value[x, y]
+
+  for y in range(t_y - 1, -1, -1):
+    path[index, y] = 1
+    if index != 0 and (index == y or value[index, y-1] < value[index-1, y-1]):
+      index = index - 1
+
+
+@cython.boundscheck(False)
+@cython.wraparound(False)
+cpdef void maximum_path_c(int[:,:,::1] paths, float[:,:,::1] values, int[::1] t_xs, int[::1] t_ys, float max_neg_val=-1e9) nogil:
+  cdef int b = values.shape[0]
+
+  cdef int i
+  for i in prange(b, nogil=True):
+    maximum_path_each(paths[i], values[i], t_xs[i], t_ys[i], max_neg_val)
diff --git a/egs/ljspeech/TTS/matcha/monotonic_align/setup.py b/egs/ljspeech/TTS/matcha/monotonic_align/setup.py
new file mode 100644
index 000000000..f22bc6a35
--- /dev/null
+++ b/egs/ljspeech/TTS/matcha/monotonic_align/setup.py
@@ -0,0 +1,7 @@
+# from distutils.core import setup
+# from Cython.Build import cythonize
+# import numpy
+
+# setup(name='monotonic_align',
+#       ext_modules=cythonize("core.pyx"),
+#       include_dirs=[numpy.get_include()])