In this study, we present detailed molecular-level structural models of amylin 20-29 and Aβ 25-35 fibrils determined using MD simulations that are based on C--O bond and ψdihedral angle constraints measured by Raman spectroscopy. The agreement between our fibril models of amylin 20-29 polymorphs 1 and 2 with those reported by the Landsbury, Griffin, Middleton, and Nielsen groups highlight the potential to develop quantitative molecular structural models of fibrils using Raman spectroscopy. It also highlights the fact that our approach provides structural information that complements gold-standard techniques such as ssNMR and cryo-EM.