diff --git a/kernel/gzip.cc b/kernel/gzip.cc
new file mode 100644
index 00000000000..d69d5764edb
--- /dev/null
+++ b/kernel/gzip.cc
@@ -0,0 +1,109 @@
+#include "kernel/yosys_common.h"
+#include "kernel/log.h"
+#include "kernel/gzip.h"
+#include <iostream>
+#include <dirent.h>
+#include <string>
+#include <cstdarg>
+#include <cstdio>
+
+YOSYS_NAMESPACE_BEGIN
+
+
+#ifdef YOSYS_ENABLE_ZLIB
+
+PRIVATE_NAMESPACE_BEGIN
+
+using namespace Zlib;
+
+static const size_t GZ_BUFFER_SIZE = 8192;
+static void decompress_gzip(const std::string &filename, std::stringstream &out)
+{
+    char buffer[GZ_BUFFER_SIZE];
+    int bytes_read;
+    gzFile gzf = gzopen(filename.c_str(), "rb");
+    while(!gzeof(gzf)) {
+        bytes_read = gzread(gzf, reinterpret_cast<void *>(buffer), GZ_BUFFER_SIZE);
+        out.write(buffer, bytes_read);
+    }
+    gzclose(gzf);
+}
+
+PRIVATE_NAMESPACE_END
+
+gzip_ostream::gzip_ostream() : std::ostream(nullptr) {
+    rdbuf(&outbuf);
+}
+
+bool gzip_ostream::open(const std::string &filename) {
+    return outbuf.open(filename);
+}
+
+gzip_ostream::gzip_streambuf::gzip_streambuf() {
+    setp(buffer, buffer + buffer_size - 1);
+}
+
+bool gzip_ostream::gzip_streambuf::open(const std::string &filename) {
+    gzf = gzopen(filename.c_str(), "wb");
+    return gzf != nullptr;
+}
+
+int gzip_ostream::gzip_streambuf::sync() {
+    int num = pptr() - pbase();
+    if (num > 0) {
+        if (gzwrite(gzf, reinterpret_cast<const void*>(pbase()), num) != num) {
+            return -1;
+        }
+        pbump(-num);
+    }
+    return 0;
+}
+
+gzip_ostream::gzip_streambuf::~gzip_streambuf() {
+    if (gzf) {
+        sync();
+        gzclose(gzf);
+    }
+}
+
+#endif // YOSYS_ENABLE_ZLIB
+
+
+// Takes a successfully opened ifstream. If it's gzipped, returns an istream
+// over a buffer of the file fully decompressed in memory. Otherwise,
+// returns the original ifstream, rewound to the start.
+std::istream* uncompressed(std::ifstream* f, const std::string filename) {
+	if (!f)
+		return nullptr;
+	// Check for gzip magic
+	unsigned char magic[3];
+	int n = 0;
+	while (n < 3)
+	{
+		int c = f->get();
+		if (c != EOF) {
+			magic[n] = (unsigned char) c;
+		}
+		n++;
+	}
+	if (n == 3 && magic[0] == 0x1f && magic[1] == 0x8b) {
+#ifdef YOSYS_ENABLE_ZLIB
+		log("Found gzip magic in file `%s', decompressing using zlib.\n", filename.c_str());
+		if (magic[2] != 8)
+			log_cmd_error("gzip file `%s' uses unsupported compression type %02x\n",
+				filename.c_str(), unsigned(magic[2]));
+    delete f;
+		std::stringstream *df = new std::stringstream();
+		decompress_gzip(filename, *df);
+		return df;
+#else
+		log_cmd_error("File `%s' is a gzip file, but Yosys is compiled without zlib.\n", filename.c_str());
+#endif // YOSYS_ENABLE_ZLIB
+	} else {
+		f->clear();
+		f->seekg(0, std::ios::beg);
+		return f;
+	}
+}
+
+YOSYS_NAMESPACE_END
diff --git a/kernel/gzip.h b/kernel/gzip.h
index 5bc517d06ee..61558590142 100644
--- a/kernel/gzip.h
+++ b/kernel/gzip.h
@@ -36,6 +36,76 @@ class gzip_ostream : public std::ostream {
 
     gzip_streambuf outbuf;  // The stream buffer instance
 };
+
+/*
+An input stream that uses zlib to read gzip-compressed data from a file,
+buffering the decompressed data internally using a stringbuf.
+*/
+class gzip_istream final : public std::istream {
+public:
+    gzip_istream() : std::istream(&inbuf) {}
+
+    bool open(const std::string& filename) {
+        return inbuf.open(filename);
+    }
+
+private:
+    class gzip_streambuf final : public std::streambuf {
+    public:
+        gzip_streambuf() : gzf(nullptr) {}
+
+        bool open(const std::string& filename) {
+            if (gzf) {
+                Zlib::gzclose(gzf);
+            }
+            gzf = Zlib::gzopen(filename.c_str(), "rb");
+            if (!gzf) {
+                return false;
+            }
+            // Set up the get buffer
+            setg(buffer,        // beginning of buffer
+                 buffer,        // current position
+                 buffer);       // end position (initially empty)
+            return true;
+        }
+        virtual ~gzip_streambuf() {
+            if (gzf) {
+                Zlib::gzclose(gzf);
+            }
+        }
+
+    protected:
+        // Called when the buffer is empty and more input is needed
+        virtual int_type underflow() override {
+            if (gzf == nullptr) {
+                return traits_type::eof();
+            }
+            int bytes_read = Zlib::gzread(gzf, buffer, buffer_size);
+            if (bytes_read <= 0) {
+                // An error occurred during reading
+                int err;
+                const char* error_msg = Zlib::gzerror(gzf, &err);
+				if (err != Z_STREAM_END)
+					log_error("%s", error_msg);
+                return traits_type::eof();
+            }
+
+            // Reset buffer pointers
+            setg(buffer,        // beginning of buffer
+                 buffer,        // current position
+                 buffer + bytes_read); // end position
+            return traits_type::to_int_type(buffer[0]);
+        }
+
+    private:
+        static const int buffer_size = 4096;
+        char buffer[buffer_size];
+        Zlib::gzFile gzf;
+    };
+
+    gzip_streambuf inbuf;  // The stream buffer instance
+};
+
 #endif // YOSYS_ENABLE_ZLIB
 
 std::istream* uncompressed(std::ifstream* f, const std::string filename);