diff --git a/cmake/SfizzSIMDSourceFilesCheck.cmake b/cmake/SfizzSIMDSourceFilesCheck.cmake
index 1237b3bc..3c88f5b2 100644
--- a/cmake/SfizzSIMDSourceFilesCheck.cmake
+++ b/cmake/SfizzSIMDSourceFilesCheck.cmake
@@ -10,7 +10,7 @@ endif()
 # SIMD checks
 if (HAVE_X86INTRIN_H AND UNIX)
     add_compile_options (-DHAVE_X86INTRIN_H)
-    set (SFIZZ_SIMD_SOURCES sfizz/SIMDSSE.cpp)
+    set (SFIZZ_SIMD_SOURCES sfizz/SIMDSSE.cpp sfizz/OversamplerSSE.cpp)
 elseif (HAVE_INTRIN_H AND WIN32)
     add_compile_options (/DHAVE_INTRIN_H)
     set (SFIZZ_SIMD_SOURCES sfizz/SIMDSSE.cpp)
@@ -20,9 +20,9 @@ elseif (HAVE_ARM_NEON_H AND UNIX)
     add_compile_options (-march=native)
     add_compile_options (-mtune=cortex-a53)
     add_compile_options (-funsafe-math-optimizations)
-    set (SFIZZ_SIMD_SOURCES sfizz/SIMDDummy.cpp)
+    set (SFIZZ_SIMD_SOURCES sfizz/SIMDDummy.cpp sfizz/OversamplerDummy.cpp)
 else()
-    set (SFIZZ_SIMD_SOURCES sfizz/SIMDDummy.cpp)
+    set (SFIZZ_SIMD_SOURCES sfizz/SIMDDummy.cpp sfizz/OversamplerDummy.cpp)
 endif()
 
 set (SFIZZ_SOURCES ${SFIZZ_SOURCES} ${SFIZZ_SIMD_SOURCES})
diff --git a/src/sfizz/Config.h b/src/sfizz/Config.h
index 9176f6e0..9087d0b0 100644
--- a/src/sfizz/Config.h
+++ b/src/sfizz/Config.h
@@ -65,5 +65,6 @@ namespace SIMDConfig {
     constexpr bool sfzInterpolationCast { true };
     constexpr bool mean { false };
     constexpr bool meanSquared { false };
+    constexpr bool upsampling { false };
 }
 } // namespace sfz
diff --git a/src/sfizz/Oversampler.h b/src/sfizz/Oversampler.h
new file mode 100644
index 00000000..68953be6
--- /dev/null
+++ b/src/sfizz/Oversampler.h
@@ -0,0 +1,95 @@
+// Copyright (c) 2019, Paul Ferrand
+// All rights reserved.
+
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are met:
+
+// 1. Redistributions of source code must retain the above copyright notice, this
+//    list of conditions and the following disclaimer.
+// 2. Redistributions in binary form must reproduce the above copyright notice,
+//    this list of conditions and the following disclaimer in the documentation
+//    and/or other materials provided with the distribution.
+
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
+// ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+// ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#pragma once
+#include <array>
+#include "absl/types/span.h"
+#include "Debug.h"
+#include "Config.h"
+#include "hiir/Upsampler2xFpu.h"
+
+namespace sfz {
+
+constexpr std::array<double, 12> coeffsStage2x {
+    0.036681502163648017,
+    0.13654762463195771,
+    0.27463175937945411,
+    0.42313861743656667,
+    0.56109869787919475,
+    0.67754004997416162,
+    0.76974183386322659,
+    0.83988962484963803,
+    0.89226081800387891,
+    0.9315419599631839,
+    0.96209454837808395,
+    0.98781637073289708
+};
+
+constexpr std::array<double, 4> coeffsStage4x {
+    0.042448989488488006,
+    0.17072114107630679,
+    0.39329183835224008,
+    0.74569514831986694
+};
+
+constexpr std::array<double, 3> coeffsStage8x {
+    0.055748680811302048,
+    0.24305119574153092,
+    0.6466991311926823
+};
+
+template<bool SIMD=SIMDConfig::upsampling>
+inline void upsample2xStage(absl::Span<const float> input, absl::Span<float> output)
+{
+    ASSERT(output.size() >= 2 * input.size());
+    hiir::Upsampler2xFpu<coeffsStage2x.size()> upsampler;
+    upsampler.set_coefs(coeffsStage2x.data());
+    upsampler.process_block(output.data(), input.data(), input.size());
+}
+
+
+template<bool SIMD=SIMDConfig::upsampling>
+inline void upsample4xStage(absl::Span<const float> input, absl::Span<float> output)
+{
+    ASSERT(output.size() >= 2 * input.size());
+    hiir::Upsampler2xFpu<coeffsStage4x.size()> upsampler;
+    upsampler.set_coefs(coeffsStage4x.data());
+    upsampler.process_block(output.data(), input.data(), input.size());
+}
+
+template<bool SIMD=SIMDConfig::upsampling>
+inline void upsample8xStage(absl::Span<const float> input, absl::Span<float> output)
+{
+    ASSERT(output.size() >= 2 * input.size());
+    hiir::Upsampler2xFpu<coeffsStage8x.size()> upsampler;
+    upsampler.set_coefs(coeffsStage8x.data());
+    upsampler.process_block(output.data(), input.data(), input.size());
+}
+
+template<>
+inline void upsample2xStage<true>(absl::Span<const float> input, absl::Span<float> output);
+template<>
+inline void upsample4xStage<true>(absl::Span<const float> input, absl::Span<float> output);
+template<>
+inline void upsample8xStage<true>(absl::Span<const float> input, absl::Span<float> output);
+}
diff --git a/src/sfizz/OversamplerDummy.cpp b/src/sfizz/OversamplerDummy.cpp
new file mode 100644
index 00000000..b92477b5
--- /dev/null
+++ b/src/sfizz/OversamplerDummy.cpp
@@ -0,0 +1,40 @@
+// Copyright (c) 2019, Paul Ferrand
+// All rights reserved.
+
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are met:
+
+// 1. Redistributions of source code must retain the above copyright notice, this
+//    list of conditions and the following disclaimer.
+// 2. Redistributions in binary form must reproduce the above copyright notice,
+//    this list of conditions and the following disclaimer in the documentation
+//    and/or other materials provided with the distribution.
+
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
+// ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+// ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include "Oversampler.h"
+
+template<>
+inline void sfz::upsample2xStage<true>(absl::Span<const float> input, absl::Span<float> output)
+{
+    sfz::upsample2xStage<false>(input, output);
+}
+template<>
+inline void sfz::upsample4xStage<true>(absl::Span<const float> input, absl::Span<float> output)
+{
+    sfz::upsample4xStage<false>(input, output);
+}
+template<>
+inline void sfz::upsample8xStage<true>(absl::Span<const float> input, absl::Span<float> output)
+{
+    sfz::upsample8xStage<false>(input, output);
+}
diff --git a/src/sfizz/OversamplerSSE.cpp b/src/sfizz/OversamplerSSE.cpp
new file mode 100644
index 00000000..f3617a02
--- /dev/null
+++ b/src/sfizz/OversamplerSSE.cpp
@@ -0,0 +1,50 @@
+// Copyright (c) 2019, Paul Ferrand
+// All rights reserved.
+
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are met:
+
+// 1. Redistributions of source code must retain the above copyright notice, this
+//    list of conditions and the following disclaimer.
+// 2. Redistributions in binary form must reproduce the above copyright notice,
+//    this list of conditions and the following disclaimer in the documentation
+//    and/or other materials provided with the distribution.
+
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
+// ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+// ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include "Oversampler.h"
+#include "hiir/Upsampler2x4Sse.h"
+
+template<>
+inline void sfz::upsample2xStage<true>(absl::Span<const float> input, absl::Span<float> output)
+{
+    ASSERT(output.size() >= 2 * input.size());
+    hiir::Upsampler2x4Sse<sfz::coeffsStage2x.size()> upsampler;
+    upsampler.set_coefs(sfz::coeffsStage2x.data());
+    upsampler.process_block(output.data(), input.data(), input.size());
+}
+template<>
+inline void sfz::upsample4xStage<true>(absl::Span<const float> input, absl::Span<float> output)
+{
+    ASSERT(output.size() >= 2 * input.size());
+    hiir::Upsampler2x4Sse<sfz::coeffsStage4x.size()> upsampler;
+    upsampler.set_coefs(sfz::coeffsStage4x.data());
+    upsampler.process_block(output.data(), input.data(), input.size());
+}
+template<>
+inline void sfz::upsample8xStage<true>(absl::Span<const float> input, absl::Span<float> output)
+{
+    ASSERT(output.size() >= 2 * input.size());
+    hiir::Upsampler2x4Sse<sfz::coeffsStage8x.size()> upsampler;
+    upsampler.set_coefs(sfz::coeffsStage8x.data());
+    upsampler.process_block(output.data(), input.data(), input.size());
+}