diff --git a/Project.toml b/Project.toml
index fd0882e97e..9623428c29 100644
--- a/Project.toml
+++ b/Project.toml
@@ -42,6 +42,7 @@ LLVM = "6.1, 7, 8, 9"
 LogExpFunctions = "0.3"
 ObjectFile = "0.4"
 Preferences = "1.4"
+SparseArrays = "1"
 SpecialFunctions = "1, 2"
 StaticArrays = "1"
 julia = "1.10"
diff --git a/src/Enzyme.jl b/src/Enzyme.jl
index b49c3738f6..091021cb8b 100644
--- a/src/Enzyme.jl
+++ b/src/Enzyme.jl
@@ -98,6 +98,7 @@ export jacobian, gradient, gradient!, hvp, hvp!, hvp_and_gradient!
 export markType, batch_size, onehot, chunkedonehot
 
 using LinearAlgebra
+import SparseArrays
 import EnzymeCore: ReverseMode, ReverseModeSplit, ForwardMode, Mode
 
 import EnzymeCore: EnzymeRules
diff --git a/src/internal_rules.jl b/src/internal_rules.jl
index f8c6e730bb..b6d081d57d 100644
--- a/src/internal_rules.jl
+++ b/src/internal_rules.jl
@@ -724,6 +724,133 @@ function EnzymeRules.reverse(
     return (nothing, nothing)
 end
 
+
+function EnzymeRules.augmented_primal(config::EnzymeRules.RevConfig, 
+                                      func::Const{typeof(LinearAlgebra.mul!)},
+                                      ::Type{RT}, 
+                                      C::Annotation{<:StridedVecOrMat},
+                                      A::Const{<:SparseArrays.SparseMatrixCSCUnion},
+                                      B::Annotation{<:StridedVecOrMat},
+                                      α::Annotation{<:Number},
+                                      β::Annotation{<:Number}
+                                    ) where {RT}
+
+    cache_C = !(isa(β, Const)) ? copy(C.val) : nothing
+    # Always need to do forward pass otherwise primal may not be correct
+    func.val(C.val, A.val, B.val, α.val, β.val)
+
+    primal = if EnzymeRules.needs_primal(config)
+        C.val
+    else
+        nothing
+    end
+
+    shadow = if EnzymeRules.needs_shadow(config)
+        C.dval
+    else
+        nothing
+    end
+
+    # Check if A is overwritten and B is active (and thus required)
+    cache_A = ( EnzymeRules.overwritten(config)[5]
+                && !(typeof(B) <: Const)
+                && !(typeof(C) <: Const)
+                ) ? copy(A.val) : nothing
+    
+    # cache_B = ( EnzymeRules.overwritten(config)[6]) ? copy(B.val) : nothing
+
+    if !isa(α, Const)
+        cache_α = A.val*B.val
+    else
+        cache_α = nothing
+    end
+    
+    cache = (cache_C, cache_A, cache_α)
+
+    return EnzymeRules.AugmentedReturn(primal, shadow, cache)
+end
+
+function EnzymeRules.reverse(config::EnzymeRules.RevConfig,
+                             func::Const{typeof(LinearAlgebra.mul!)},
+                             ::Type{RT}, cache,
+                             C::Annotation{<:StridedVecOrMat},
+                             A::Const{<:SparseArrays.SparseMatrixCSCUnion},
+                             B::Annotation{<:StridedVecOrMat},
+                             α::Annotation{<:Number},
+                             β::Annotation{<:Number}
+                             ) where {RT}
+
+    cache_C, cache_A, cache_α = cache
+    Cval = !isnothing(cache_C) ? cache_C : C.val
+    Aval = !isnothing(cache_A) ? cache_A : A.val
+    # Bval = !isnothing(cache_B) ? cache_B : B.val
+
+    N = EnzymeRules.width(config)
+    if !isa(C, Const)
+        dCs = C.dval
+        dBs  = isa(B, Const) ? dCs : B.dval
+
+        dα = if !isa(α, Const)
+                if N == 1
+                    LinearAlgebra.dot(C.dval, cache_α)
+                else
+                    ntuple(Val(N)) do i
+                        Base.@_inline_meta
+                        LinearAlgebra.dot(C.dval[i], cache_α)
+                    end
+                end
+        else
+            nothing
+        end
+
+        dβ = if !isa(β, Const)
+                if N == 1
+                    LinearAlgebra.dot(C.dval, Cval)
+                else
+                    ntuple(Val(N)) do i
+                        Base.@_inline_meta
+                        LinearAlgebra.dot(C.dval[i], Cval)
+                    end
+                end
+        else
+            nothing
+        end
+
+        for i in 1:N
+            # This rule is incorrect since you need to project dA to have the same
+            # sparsity pattern as A.
+            # if !isa(A, Const)
+            #     dA = EnzymeRules.width(config) == 1 ? A.dval : A.dval[b]
+            #     #dA .+= α*dC*B'
+            #     mul!(dA, dC, Bval', α.val, true)
+            # end
+
+            if !isa(B, Const)
+                #dB .+= α*A'*dC
+                if N ==1
+                    func.val(dBs, Aval', dCs, α.val, true)
+                else
+                    func.val(dBs[i], Aval', dCs[i], α.val, true)
+                end
+            end
+
+            if N==1
+                dCs .*= β.val
+            else
+                dCs[i] .*= β.val
+            end
+        end
+    end
+   
+    return (nothing, nothing, nothing, dα, dβ)
+end
+
+
+
+
+
+
+
 function EnzymeRules.forward(
     config::EnzymeRules.FwdConfig,
     ::Const{typeof(sort!)},
@@ -1269,4 +1396,4 @@ function EnzymeRules.reverse(
     smpl::Annotation{<:Random.SamplerTrivial{Random.CloseOpen01{FT}}},
 ) where {rngty<:Union{TaskLocalRNG,Xoshiro},FT<:Union{Float32,Float64}}
     return (nothing, nothing, nothing)
-end
+end
\ No newline at end of file
diff --git a/test/internal_rules.jl b/test/internal_rules.jl
index 0d5bbdae01..246929272b 100644
--- a/test/internal_rules.jl
+++ b/test/internal_rules.jl
@@ -677,4 +677,46 @@ end
     # @test Enzyme.autodiff(Reverse, (x, y) -> begin y[] = f4(x); nothing end,  Active(0.1), BatchDuplicated(Ref(0.0), (Ref(1.0), Ref(2.0)))) == (((0.0,0.0)),)
 end
 
+@testset "SparseArrays spmatvec reverse rule" begin
+    C = zeros(18)
+    M = sprand(18, 9, 0.1)
+    v = randn(9)
+    α = 2.0
+    β = 1.0
+
+    for Tret in (Duplicated, BatchDuplicated), Tv in (Const, Duplicated, BatchDuplicated), 
+        Tα in (Const, Active), Tβ in (Const, Active)
+
+        are_activities_compatible(Tret, Tret, Tv, Tα, Tβ) || continue
+        test_reverse(LinearAlgebra.mul!, Tret, (C, Tret), (M, Const), (v, Tv), (α, Tα), (β, Tβ))
+
+    end
+
+
+    for Tret in (Duplicated, BatchDuplicated), Tv in (Const, Duplicated, BatchDuplicated), bα in (true, false), bβ in (true, false)
+        are_activities_compatible(Tret, Tret, Tv) || continue
+        test_reverse(LinearAlgebra.mul!, Tret, (C, Tret), (M, Const), (v, Tv), (bα, Const), (bβ, Const))
+    end
+end
+
+@testset "SparseArrays spmatmat reverse rule" begin
+    C = zeros(18, 11)
+    M = sprand(18, 9, 0.1)
+    v = randn(9, 11)
+    α = 2.0
+    β = 1.0
+
+    for Tret in (Duplicated, BatchDuplicated), Tv in (Const, Duplicated, BatchDuplicated), 
+        Tα in (Const, Active), Tβ in (Const, Active)
+
+        are_activities_compatible(Tret, Tv, Tα, Tβ) || continue
+        test_reverse(LinearAlgebra.mul!, Tret, (C, Tret), (M, Const), (v, Tv), (α, Tα), (β, Tβ))
+    end
+
+    for Tret in (Duplicated, BatchDuplicated), Tv in (Const, Duplicated, BatchDuplicated), bα in (true, false), bβ in (true, false)
+        are_activities_compatible(Tret, Tv) || continue
+        test_reverse(LinearAlgebra.mul!, Tret, (C, Tret), (M, Const), (v, Tv), (bα, Const), (bβ, Const))
+    end
+end
+
 end # InternalRules
diff --git a/test/runtests.jl b/test/runtests.jl
index d499febd77..bd1c7dd90d 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -4101,4 +4101,4 @@ include("ext/logexpfunctions.jl")
 
 @testset "BFloat16s ext" begin
     include("ext/bfloat16s.jl")
-end
+end
\ No newline at end of file